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Although the long-acting opiate methadone is commonly used to treat drug addiction, relatively little is known about the effects of withdrawal from this drug in preclinical models. The current study examined affective, neuroendocrine, and somatic signs of withdrawal from the longer-acting methadone derivative l-alpha-acetylmethydol (LAAM) in rats. Anxiety-like behavior during both spontaneous and antagonist-precipitated withdrawal was measured by potentiation of the startle reflex. Withdrawal elevated corticosterone and somatic signs and blunted circadian variations in baseline startle responding. In addition, fear to an explicit, Pavlovian conditioned stimulus (fear-potentiated startle) was enhanced. These data suggest that anxiety-like behavior as measured using potentiated startle responding does not emerge spontaneously during withdrawal from chronic opiate exposure – in contrast to withdrawal from acute drug exposure – but rather is manifested as exaggerated fear in response to explicit threat cues.

The trigger for liver regeneration, including shear stress, has been the subject of ongoing debate. Blood vessel-derived gaseous molecules carbon monoxide (CO) and nitric oxide (NO) regulate vascular tone and play an important role in liver regeneration. In heme oxygenase-1 (HO-1) transgenic mice, it has been shown that CO-mediated impairment of vasorelaxation is an NO-dependent event. We therefore studied liver regeneration in HO-1 overexpressing animals in dependency of NO availability. Mice were subjected to (2/3) hepatectomy and were treated with either cobalt protoporphyrin-IX for induction of CO-liberating HO-1, N(omega)-nitro-L-arginine methyl ester (L-NAME) for blockade of NO synthase (NOS) or both. Application of molsidomine in L-NAME treated animals served for resubstitution of NO. Vehicle-treated animals served as respective control animals. We examined 5-bromo-2'-deoxyuridine incorporation and proliferating cell nuclear antigen expression as well as HO-1 and NOS-2 protein levels. Intrahepatic red blood cell velocity and volumetric blood flow were evaluated by in vivo fluorescence microscopy as indicators for microvascular shear stress. Hepatic regeneration remained unaffected by L-NAME application for NOS blockade. However, NOS blockade in HO-1 induced animals caused increased 5-bromo-2'-deoxyuridine and proliferating cell nuclear antigen measures of liver regeneration. In parallel, these animals revealed increased velocities and volumetric blood flow in the terminal afferent vessels and postsinusoidal venules. These local hemodynamic changes including enhanced hepatocyte proliferation could be reversed by NO liberation via molsidomine. The present findings stress the role of NO to counterbalance vascular tone in HO-1 overexpressing animals for maintenance of adequate perfusion and salutary shear force within the hepatic microvasculature upon liver resection.

Retention in Opioid Agonist Therapy (OAT) is associated with reductions in substance use, HIV risk behavior, and criminal activities in opioid dependent patients. To improve the effectiveness of treatment for opioid dependence, it is important to identify predisposing characteristics and provider-related variables that predict retention in OAT. Participants include 258 veterans enrolled in 8 outpatient methadone/l-alpha-acetylmethadol (LAAM) treatment programs. Signal detection analysis was utilized to identify variables predictive of 1-year retention and to identify the optimal cut-offs for significant predictors. Provider-related variables play a vital role in predicting retention in OAT programs, as higher methadone dose (> or =59 mg/day) and greater treatment satisfaction were among the strongest predictors of retention at 1-year follow-up.

We evaluated a case management intervention to increase treatment entry among injecting drug users referred from a needle exchange program (NEP). A randomized trial of a strengths based case management (intervention) versus passive referral (control) was conducted among NEP attenders requesting and receiving referrals to subsidized, publicly funded opiate agonist treatment programs in Baltimore, MD. Logistic regression identified predictors of treatment entry within 7 days, confirmed through treatment program records. Of 247 potential subjects, 245 (99%) participated. HIV prevalence was 19%. Overall, 34% entered treatment within 7 days (intervention: 40% versus control: 26%, p = 0.03). In a multivariate “intention to treat’ model (i.e., ignoring the amount of case management actually received), those randomized to case management were more likely to enter treatment within 7 days. Additional ‘as treated’ analyses revealed that participants who received 30 min or more of case management within 7 days were 33% more likely to enter treatment and the active ingredient of case management activities was provision of transportation. These findings demonstrate the combined value of offering dedicated treatment referrals from NEP, case management and transportation in facilitating entry into drug abuse treatment. Such initiatives could be implemented at more than 140 needle exchange programs currently operating in the United States. These data also support the need for more accessible programs such as mobile or office-based drug abuse treatment.

Opioid- and cocaine-dependent participants ( N = 140) were randomly assigned to one of the following in a 12-week clinical trial: LAAM (30, 30, 39 mg/MWF) with contingency management (CM) procedures (LC); LAAM (30, 30, 39 mg/MWF) without CM (LY); LAAM (100, 100, 130 mg/MWF) with CM (HC); LAAM (100, 100, 130 mg/MWF) without CM (HY). Urine samples were collected thrice-weekly. In CM, each urine negative for both opioids and cocaine resulted in a voucher worth a certain monetary value that increased for consecutively drug-free urines. Subjects not assigned to CM received vouchers according to a yoked schedule. Vouchers were exchanged for mutually agreed upon goods and services. Groups generally did not differ on retention and baseline characteristics. Overall opioid use was least in the HC and HY groups; opioid use decreased most rapidly over time in the HC group relative to the HY, LC and LY groups. Overall cocaine use was least in the HC group relative to the HY, LC, and LY groups; cocaine use decreased over time most rapidly in the HC and LY groups. Abstinence from both was greatest in the HC group. Opioid withdrawal symptoms decreased most rapidly in the high-dose groups relative to the low-dose groups. These results suggest that an efficacious maintenance dose is necessary for contingencies to be effective in facilitating both opioid and cocaine abstinence.

We examined the effects of prenatal exposure to the long acting opiate l-alpha-acetylmethadol (LAAM) followed by postnatal withdrawal on hypothalamic-pituitary-adrenal (HPA) axis reactivity in neonatal and adult rats and anxiety-like behavior in adult rats. Female rats were treated with LAAM (0, 0.2, or 1.0 mg/kg/day) via oral gavage for 28 days prior to and continuing throughout pregnancy. Pups were fostered at birth to nontreated, lactating dams and underwent opiate withdrawal. On postnatal day (PND) 18, prenatal opiate-exposed male and female rat pups displayed a decreased corticosterone response 2 h after the application of an immunological stressor and 15 min following a social stressor compared to controls. In contrast, in adulthood, prenatal opiate-treated rats showed a heightened corticosterone response compared to prenatal water-treated controls at 3 h, but not 8 h, following an immunological stressor. Males prenatally treated with 1.0 mg/kg LAAM displayed elevated startle responding compared to the other prenatally treated male groups, but there was no effect of prenatal treatment in females. There were no effects of prenatal treatment in the open field test in either sex. These results suggest that prenatal opiate exposure followed by postnatal withdrawal dysregulated the HPA axis response to stressors in the neonate and adult and differentially affected adult anxiety-like behavior in males and females.

Opiate addiction is a chronic, relapsing disorder. Left untreated, high morbidity and mortality rates are seen. Pharmacotherapies for this disorder using mu opiate agonists (methadone and levomethadyl acetate) and partial agonists have been developed in the last 40 years. Agonist pharmacotherapy with oral methadone for the treatment of opiate dependence was developed in clinical pharmacology studies at Rockefeller University by Dole, Nyswander, and Kreek. Further studies by this laboratory and others established that moderate to high dose treatment with methadone (80-120 mg) reduced or eliminated opiate use in outpatient settings with consequent reductions in morbidity and up to 4-fold reductions in mortality. Levomethadyl acetate (LAAM), a congener of methadone, is biotransformed to active metabolites responsible for its longer duration of action. The Federal Regulations regarding the dispensation of methadone and LAAM have recently been revised to facilitate the treatment of patients under a "medical maintenance" model. Future regulatory reform will likely involve the establishment of rules for "office based opioid treatment."

We conducted a randomized controlled trial to evaluate whether dialectical behavior therapy (DBT), a treatment that synthesizes behavioral change with radical acceptance strategies, would be more effective for heroin-dependent women with borderline personality disorder (N = 23) than Comprehensive Validation Therapy with 12-Step (CVT + 12S), a manualized approach that provided the major acceptance-based strategies used in DBT in combination with participation in 12-Step programs. In addition to psychosocial treatment, subjects also received concurrent opiate agonist therapy with adequate doses of LAAM (thrice weekly; modal dose 90/90/130 mg). Treatment lasted for 12 months. Drug use outcomes were measured via thrice-weekly urinalyses and self-report. Three major findings emerged. First, results of urinalyses indicated that both treatment conditions were effective in reducing opiate use relative to baseline. At 16 months post-randomization (4 months post-treatment), all participants had a low proportion of opiate-positive urinalyses (27% in DBT; 33% in CVT + 12S). With regard to between-condition differences, participants assigned to DBT maintained reductions in mean opiate use through 12 months of active treatment while those assigned to CVT + 12S significantly increased opiate use during the last 4 months of treatment. Second, CVT + 12S retained all 12 participants for the entire year of treatment, compared to a 64% retention rate in DBT. Third, at both post-treatment and at the 16-month follow-up assessment, subjects in both treatment conditions showed significant overall reductions in level of psychopathology relative to baseline. A noteworthy secondary finding was that DBT participants were significantly more accurate in their self-report of opiate use than were those assigned to CVT + 12S.

Effective postincarceration treatment for individuals with preincarceration heroin dependence is urgently needed because relapse typically follows release. This article presents first-year findings from a unique 2-year pilot study of opioid agonist maintenance treatment initiated in prison and continued in the community. Incarcerated males with preincarceration heroin dependence were randomly assigned to Levo-alpha-acetylmethadol (LAAM) maintenance or control conditions 3 months before release. Approximately 92% of eligible inmates volunteered to participate; 36 of 58 subjects who were eligible and randomly assigned to LAAM maintenance successfully initiated treatment. Twenty-eight of these continued on LAAM until release; 22 (78.6%) entered community-based maintenance treatment; and 11 (50%) remained in treatment at least 6 months postrelease. Changes in LAAM's labeling because of its association with cardiac arrhythmias now makes it a second-line treatment for heroin dependence, unsuitable for treatment initiation. Nonetheless, study findings may also be applicable to methadone maintenance treatment, suggesting such treatment may be a promising means of engaging prisoners with preincarceration heroin dependence into continuing treatment.

The efficacy of methadone maintenance in opioid addiction was assessed in terms of programme retention rate and reduction of illicit opioid use by means of a meta-analysis of randomised, controlled and double blind clinical trials. The results were compared with interventions using buprenorphine and levo-acetylmethadol (LAAM). Trials were identified from the PubMed database from 1966 to December 1999 using the major medical subject headings 'methadone' and 'randomised controlled trial'. Data for a total of 1944 opioid-dependent patients from 13 studies were analysed. Sixty-four percent of patients received methadone, administered either as fixed or adjusted doses. Thus, 890 patients receivedor = 50 mg/day (high dose group) and 392 were given50 mg/day (low dose group). Of 662 controls, 131 received placebo, 350 buprenorphine (265 at dosesor = 8 mg/day and 85 at doses8 mg/day) and 181 LAAM. High doses of methadone were more effective than low doses in the reduction of illicit opioid use (odds ratio [OR] 1.72, 95% confidence interval [CI] 1.26--2.36). High doses of methadone were significantly more effective than low doses of buprenorphine (8 mg/day) for retention rates and illicit opioid use, but similar to high doses of buprenorphine (or = 8 mg/day) for both parameters. Patients treated with LAAM had more risk of failure of retention than those receiving high doses of methadone (OR 1.92, 95% CI 1.32--2.78). It is proposed that in agonist-maintenance programmes, oral methadone at doses of 50 mg/day or higher is the drug of choice for opioid dependence.

Incubation of l-α-acetylmethadol (LAAM) or norLAAM with cDNA-expressed P450s 3A4, 2B6, and 2C18 produced significant N-demethylation products. P450s 2C19, 2C8, 3A5, 2C9, 3A7, 1A1, and 2D6 (norLAAM only), also produced detectable product. Coexpression of cytochrome b5 enhanced LAAM N-demethylation, most dramatically for 3A4, but had marginal effects on norLAAM N-demethylation. Modeling total liver metabolism using immunoquantification and relative activity factors of P450s suggests contributions of P450 3A4 > 2B6 > 2C18, with the importance of 2B6 to 2C isozymes enhanced by relative activity factors. The ratio of dinorLAAM to norLAAM plus dinorLAAM formed from LAAM did not exceed 20%, and was isozyme and cytochrome b5 coexpression dependent. This ratio decreased with concentration with 3A4, but was relatively constant for 2B6 and 2C18. The human liver microsomes substrate-concentration response was similar to cDNA-expressed 3A4, but the ratio was higher. Changes in the environment of cDNA-expressed 3A4 also effected the magnitude of the ratio, but not the concentration-dependent decrease. These studies show that the N-demethylation of LAAM and norLAAM is not restricted to P450 3A4, particularly P450s 2B6 and 2C18, and suggest that the mechanism of sequential metabolism for 3A4 differs from that of 2B6 and 2C18.

Levo-Alpha Acetyl Methadol, or LAAM, is a medication therapy for individuals addicted to opiates that provides an alternative to methadone. Because it is administered only three times a week and, therefore, requires fewer clinic trips, patient acceptance can be higher than with methadone. While blocking the effects of other opiates and preventing withdrawal, LAAM does not produce a subjective high. However, because most patients are not familiar with LAAM, they may be initially more anxious and need more counseling and support when receiving the medication than they would with the more familiar methadone medication. On balance, LAAM enables clinic administrators and counselors to offer an alternative medication to methadone that some clients prefer once they become adjusted to it because of LAAM's even, stable effect. Through hypothetical but true-to-life case studies of LAAM use, it is possible to gain a clearer understanding of the advantages and drawbacks of using LAAM.

A method is described for the simultaneous determination of l-alpha-acetylmethadol (LAAM) and its N-demethylated metabolites, l-alpha-noracetylmethadol (norLAAM) and l-alpha-dinoracetylmethadol (dinorLAAM), in plasma by gas chromatography-chemical ionization mass spectrometry. Deuterated internal standards for each analyte serve as carriers and control for recovery during sample purification on a solid-phase extraction column (C18), and subsequent separation and analysis on a DB-17 capillary column. With this method, we have determined levels of LAAM, norLAAM, and dinorLAAM in small volumes of plasma (100 microliters). The limit of quantitation for all analytes was approximately 1.0 ng/g plasma and the limit of detection was approximately 0.5 ng/g plasma. An experimental application is also described where these analytes are quantitated in plasma obtained from rats before, during, and after chronic administration of LAAM-HCl. Since this technique affords a selective and sensitive means of detection of LAAM and its active, N-demethylated metabolites in small samples of blood, it may enable patient compliance to be more easily assessed by allowing samples to be collected by a simple finger-prick technique.

Levo-alpha-acetylmethadol (LAAM, 0.2 or 2.0 mg/kg/day) was orally administered to female Sprague-Dawley rats for one month prior to and throughout pregnancy. The rats were killed on the 18th day of gestation along with a group of 18-day pregnant females given a single oral 2.0 mg/kg dose of LAAM 24 hours earlier. Although cumulation of LAAM or its active metabolites was not seen in plasma or brain of pregnant rats given drug chronically, significant cumulation was observed in whole fetus and in fetal brain. In addition, a 2–3 fold elevation in the concentrations, and an even greater elevation of total content, was noted in the newborn pup. These data suggest that opiate intoxication soon after birth may be a factor responsible for the increased morbidity and mortality of rat pups prenatally exposed to LAAM.

A procedure is described for the simultaneous measurement of l-α-acetylmethadol and its two pharmacologically active metabolites: noracetylmethadol and dinoracetylmethadol. In the method an intramolecular conversion reaction of the two metabolites to their amide configuration is utilized. The reaction is performed while the metabolites are still in the serum. Following solvent extraction the samples are analyzed by capillary gas—liquid chromatography coupled with nitrogen detection. Quantitation is achieved by internal standardization. The lower limit of sensitivity is 5 ng/ml in serum. Absolute sensitivity is 0.1 ng for all three compounds. The advantages over other procedures are: (1) speed due to the single extraction step; (2) increased recovery of noracetylmethadol and dinoracetylmethadol due to decreased polarity of the amides; (3) greater stability of the metabolites in the amide configuration; (4) better chromatographic quantitation and separation because detector response for the amides is greater than it is for the original configuration of the metabolites and the area of the chromatographic tracing is free of interfering substances.

The ability of l-α-acetylmethadol (LAAM) to induce ocular opacities was studied in rats. Between the third and fifth days after subcutaneous or oral administration of a single dose of LAAM, a dose-dependent incidence of opacification of the anterior segments of rat eyes was observed. Observation of the eyes of LAAM-treated rats, using a dissection microscope and a slit beam biomicroscope, indicated that the opacities were localized to the cornea and the depth of corneal involvement varied from patches of grayish epithelium to full-thickness involvement. Light microscopy of eye sections from rats given LAAM, 20 mg/kg orally, revealed corneal changes ranging from thickening and loss of regularity of epithelial cell layers to stromal vascularization and spindle cell infiltration. The sc and oral ED-50 for LAAM-induced corneal opacities was found to be 4.7 (4.2–5.3) and 12.6 (9.8–16.1) mg/kg, respectively. This is similar to or lower than the ED-50 for pharmacological effects of LAAM such as analgesia and mydriasis. The mechanism(s) by which LAAM initiates the corneal opacities is unknown. However, in rats made tolerant to morphine by implantation of a morphine pellet, we observed a threefold tolerance to LAAM-induced corneal opacities, suggesting a central nervous system mechanism in the development of the observed corneal changes.

In each of three components of a multiple schedule, monkeys were required to emit a different sequence of four responses in a predetermined order on four levers. Sequence completions produced food on a fixed-ratio schedule. Errors produced a brief timeout. One component of the multiple schedule was a repeated-acquisition task where the four-response sequence changed each session (learning). The second component of the multiple schedule was also a repeated-acquisition task, but acquisition was supported through the use of a stimulus fading procedure (faded learning). In a third component of the multiple schedule, the sequence of responses remained the same from session to session (performance). At high doses, each drug tested produced essentially the same effect. In all three components, response rate was substantially decreased and percent errors increased. At lower doses, however, their effects differed. Heroin and methadone produced dose-dependent sporadic periods of pausing, but had little or no effect on the accuracy of responding. LAAM also produced sporadic periods of pausing, but its effects on accuracy were variable. In contrast, cyclazocine produced no such pauses in responding but rather decreased the local rates of correct responding in a dose-related manner. These same doses of cyclazocine increased percent errors in the learning component, but not in the faded learning or performance components. The results are generally consistent with the view that putative mu opioid agonists do not affect the accuracy of a discrimination in monkeys except at those doses which produce a substantial decrease in the overall rate of responding.

Naloxone induced jumping was examined in mice pretreated with single dose of narcotic agonist (morphine, heroin, LAAM, methadone), mixed agonist-antagonist (pentazocine, cyclazocine, buprenorphine), or an enkephalin analog (D-met 2 , pro 5 )-enkephalinamide. Acute sensitization to naloxone, as demonstrated by jumping, was observed after pretreatment with the narcotics, the enkephalin analog, and to a lesser degree after cyclazocine and pentazocine. Mice pretreated with buprenorphine did not jump in response to naloxone. This procedure may be of value in the rapid identification of drugs with a propensity to produce morphine-like physical dependence.

Heroin addicts who had been maintained for at least three months on LAAM (levo-alpha-acetylmethadol, methadyl acetate) and at least three months on methadone were asked to compare the two drugs on a number of criteria. The responses were highly selective, indicating that a desire to please the investigators was not an important factor. Overwhelmingly, the majority of patients reported that LAAM provided better heroin “blockade”, that it was more effective in reducing craving, and that actual use of heroin was less on LAAM than on methadone. In other respects, such as sexual performance sleep, and appetite, most patients perceived no difference between the drugs. In no respect was methadone preferred by a majority, although methadone was viewed more favorably on some criteria by some patients. These findings indicate that for most heroin addicts LAAM will be an acceptable maintenance drug.

Levo-alpha-acetylmethadol (LAAM) is an orphan drug that will soon be generally available to treatment facilities. We have recently treated 959 opioid addicts with LAAM for periods up to 36 consecutive months. Three times per week dosing of LAAM proved to be a safe and effective treatment agent for the majority of subjects. During LAAM induction there is a delay in opioid activity as LAAM forms its long-acting metabolites, therefore, symptomatic withdrawal medication must usually be administered during the first 96 hours of treatment to adequately suppress opioid withdrawal symptoms and prevent self-administration of drugs by the patient. No long-term hepatic toxicity or tumor formation could be demonstrated by liver function studies and liver-spleen imaging in a subgroup of patients. Some opioid addicts report that they prefer LAAM over methadone, but the reverse was reported by about 40% of our patients which suggests that both drugs are needed for adequate maintenance treatment of the opioid-addicted population.

Therapeutic counseling has been widely adovacted with methadone maintenance, but its effectiveness has not been demonstrated. A review of the literature revealed a dearth of scientific investigations comparing treatment outcomes with and without counseling services. The few studies which have been reported seem to suggest that counseling does not significantly change treatment outcomes as measured by the usual indicators of illicit drug use, arrests, employment, and retention in the program. These studies suffered from a number of methodological flaws, however, including failure to adhere to research design, small sample size, poorly matched control groups, inadequate outcome criteria, and absence of post-treatment follow-up. Previous investigators have been nearly unanimous in calling for further studies of this issue. Since the cost of counseling services represents a major portion of treatment program budgets, there is an urgent need to document the effectiveness of these services with definitive studies.

Rats maintained dependence by the self-administration of LAAM or morphine. Following the substitution of saline for LAAM, REM sleep was not disrupted, and the frequency of lever pressing for saline self-injections peaked at about 24 hr. In contrast, following the substitution of saline for morphine, REM sleep was suppressed for 24 hr while the frequency of lever pressing for saline self-injections peaked within 8 hr. When abstinence was induced by hourly iv naloxone injections, REM sleep occurrences were suppressed to a similar degree and for similar durations during naloxone-induced abstinence from both morphine and LAAM. These results suggest that the level of physical dependence maintained during self-administration of LAAM and morphine was similar. The relatively mild abstinence syndrome that was seen during saline substitution in LAAM-dependent rats was most likely related to the long plasma half-lives of the pharmacologically active N-demethylated metabolites of LAAM.

Adult female Sprague-Dawley rats were prepared with chronic intravenous cannulas and cortical and muscle electrodes for recording electroencephalograms and electromyograms, respectively. They were made physically dependent on morphine by automatic intravenous injections and then trained to lever press in order to self-administer morphine on a FR-20 schedule of reinforcement. Upon stabilization of morphine self-administration, one group continued to self-administer morphine, while two other groups were switched to methadone or 1-alpha-acetylmethadol (LAAM) self-administration for an additional five to ten days. Continuous EEG and EMG recordings were collected. Initially, automatic injections of morphine suppressed rapid eye movement (REM) sleep time, then tolerance developed to this effect. REM sleep time in rats self-administering LAAM, methadone or morphine was within the lower limit of the normal range. Following withdrawal, REM sleep was severely suppressed during the first 24 h with morphine and methadone, but only moderately suppressed with LAAM. Increases in lever pressing during withdrawal from morphine and methadone occurred earlier and were more intense and prolonged than for LAAM. The incidence of head shakes peaked earlier and was higher for morphine and methadone during withdrawal than for LAAM. Irritability scores increased for morphine and methadone during the first day of withdrawal, but did not show any increase until the third day for LAAM. These findings suggest that in dependent rats withdrawal from LAAM is less severe than withdrawal from morphine or methadone.

Conflicting reports exist regarding the “selective” induction of rat hepatic microsomal epoxide hydratase (EH) by trans stilbene oxide ( t -SO). We reasoned that rats of differing age and sex used in previous studies could be the source of the apparent discrepancy. To clarify the effect of t -SO on the microsomal enzymes, immature male, adult male and adult female rats were used. The rats were treated with t -SO, phenobarbital, or l - α -acetylmethadol (LAAM), all inducers of EH, and the effects of age and sex on the responses of selected microsomal enzymes were determined. t -SO was found to increase benzo[ a ]pyrene hydroxylase (AHH) activity in the adult females and immature males. However, it did not increase AHH activity in the adult male. t -SO increased aminopyrene N -demethylase activity in adult males and adult females, and it elevated EH activity in all rats studied. The effects of t -SO were similar to those of phenobarbital. LAAM was found to increase EH in adult male and adult female rats; it increased AHH in the females, but not in the males. In castrated male rats, t -SO and phenobarbital affected AHH in a fashion equivalent to that observed in normal adult males. In adult males, each of the agents studied raised EH activity without a simultaneous increase in AHH activity. This “selectivity”, however, did not hold for other cytochrome P-450-dependent monooxygenases.

Selected behavioral and physiological effects of maintenance on (−)-α-acetylmethadol (LAAM) were examined for 67 men beginning LAAM maintenance. Thirty-four began LAAM maintenance after 1 month or more on methadone; 33 others were using street heroin immediately before beginning LAAM. Subjects were followed for 20 weeks on LAAM; assessment focused on changes in alcohol and diazepam use, sexual behavior and testicular function, and cardiovascular function. There was a trend toward increased alcoholism-related behaviors, but not consumption of alcohol, when on LAAM. Use of diazepam remained low. Subjects reported slightly enhanced sexual activity: reported number of ejaculations tended to increase, although interest in sexual activity remained constant. Semen volume values remained in the low normal range. In contrast to an earlier published report of reduced sperm motility in methadone and heroin users, normal motility was noted in this sample. The incidence of abnormal sperm morphology decreased from baseline to the end of the study. Cardiovascular function, as assessed by response to standard exercise, was unchanged during LAAM maintenance. Electrocardiograms revealed minor abnormalities prior to beginning LAAM maintenance ; but these abnormalities did not consistently change during treatment. There is little evidence that the effects of LAAM maintenance differ from the effects of methadone maintenance on these behavioral and physiological functions.

Prenatal exposure of rats to 0.2 mg LAAM/kg/day but not to 0.05 mg LAAM/kg/day resulted in faster hot-plate escape latencies in 6 mo old offspring. No differences in tail-flick latencies were observed at 7 mo of age in offspring exposed to either dose of LAAM prenatally. Subsequent testing of littermates at 16 mo of age revealed that the greater sensitivity to the hot-plate observed in rats prenatally exposed to LAAM is apparently a result of neonatal withdrawal rather than a primary consequence of the drug. The data are discussed in relation to possible effects of drug or withdrawal on central nervous system development.

Dependence is viewed as a dynamic state which may be altered with time respecting pattern, magnitude and quality of physical dependence, due in part to the interaction of the parent opioid with its normetabolites. The principal metabolites of acetylmethadol are noracetylmethadol and dinor-acetylmethadol; they are active morphine-like agonists, and their long half-life and accumulation in the plasma apparently account for the delayed onset of abstinence (72 h) after the acetylmethadol is withdrawn. The normetabolites of propoxyphene, norpropoxyphene and dinorpropoxyphene, are very weak morphine-like agonists. Because they accumulate in the plasma in a high ratio compared with the parent compound, they may well account, at least in part, for the relatively mild abstinence that follows propoxyphene withdrawal. Normeperidine is inactive as a morphine-like agonist and appears to have a different action in that it primarily is a convulsant. Although the formation and accumulation of normeperidine may account in part for the characteristics of its abstinence syndrome, undoubtedly a dominant factor is the disappearance of meperidine from the blood plasma (70% per hour in the dog and 17% per hour in man). In the case of normorphine, norcodeine and norlevorphanol, there is difficulty in direct addiction tests in man in elevating the dosage as compared to the parent compound, primarily because of excessive sedation and respiratory depression. Examination of the source of abstinence scores for subcutaneous normorphine, oral norcodeine, oral codeine, oral morphine, subcutaneous morphine, and oral methadone suggests that these compounds may be divided into two categories. Normorphine and norcodeine are in one category and methadone is in the other, probably because of methadone's incapacity to form active normetabolites. The relevance of the observations to comparative studies of abuse of opioids is illustrated.

1. 1. 1-α-Acetylmethadol (LAAM) and its major metabolites, 1-α-acetylnormethadol (N-LAAM) and 1-α-acetyldinormethadol (DN-LAAM) produced negative chronotropic responses in isolated right atrial preparations of three species. All species were not equally sensitive to this effect. The order of decreasing species sensitivity is: guinea-pig > rabbit > rat. 2. 2. LAAM and congeners exhibited negative inotropic properties in isolated tissue preparations. Cat and rabbit were most sensitive, followed by guinea-pig and rat. Species sensitivity to the Ca2+-antagonist effect of LAAM showed the same pattern.

Six reagents-trichloroacetyl chloride, trichloroacetic anhydride, pentafluorobenzoyl chloride, heptafluorobutyryl chloride, heptafluorobutyric anhydride, and trifluoroacetic anhydride- were evaluated as potential derivatizing reagents for quantitating the metabolites of l-alpha-acetylmethadol (LAAM) -noracetylmethadol, dinoracetylmethadol, methadol, and normethadol-by electron capture gas-liquid chromatography. All of the reagents studied reacted quantitatively with all of the metabolites except methadol; however, trichloroacetyl chloride was found to be the most satisfactory general reagent for analyzing these metabolites in biological fluids. A gas-liquid chromatographic method is presented which combines both flame ionization and electron capture detection for quantitating plasma and urine levels of methadone, l-alpha-acetylmethadol and its metabolites.

1. 1. 1-α-Acetylmethadol (LAAM) and its major metabolites, 1-α-acetylnormethadol (N-LAAM) and 1-α-acetyldinormethadol (DN-LAAM), were shown to exert significant anticholinesterase activity in preparations of guinea pig heart homogenate, guinea pig plasma, purified acetylcholinesterase (EC 3.1.1.7) and purified butyrylcholinesterase (EC 3.1.1.8), P 2. 2. LAAM and congeners did not decrease heart homogenate cholinesterase activity at low concentrations (5 × 10−6M) which produce bradycardia in vitro that can be blocked completely with atropine. 3. 3. The data suggest that cholinesterase inhibition does not contribute to the bradycardia effected by lower concentrations of LAAM. However, cholinesterase inhibition may contribute to LAAM-induced bradycardia at higher concentrations.

The distribution in vitro of (-)1-α-acetylmethadol (LAAM) in human blood constituents was studied. In concentrations close to those found in humans who are maintained on LAAM (0.35 nmole/ml serum), the drug was distributed almost evenly between plasma proteins and red blood cells. At similar concentrations of the drug in plasma alone, over 80 per cent was bound to protein. The strength of binding to proteins was very weak, as demonstrated by our inability to obtain a protein-LAAM complex by conventional Sephadex G-200 column chromatography. However, equilibration and elution of the column with buffer containing 0.35 nM drug, using [3H]LAAM as tracer, allowed the identification of a LAAM-protein complex. The fraction responsible for the bulk of LAAM binding in serum was identified as an α-globulin with a molecular weight of about 400,000. Equilibrium dialysis experiments showed that the role played by albumin in the binding of LAAM was insignificant. The binding of LAAM to serum proteins was highly reversible, as attested by the displacement of [3H]LAAM from its binding sites by unlabeled drug. The major metabolites of LAAM, noracetylmethadol and dinor-acetylmethadol, were also weakly and reversibly bound by serum proteins and competed with LAAM for protein binding sites. A Scatchard plot, after equilibrium dialysis of various concentrations of LAAM against human serum, indicates that the maximum specific binding of drug was 8.2 nmoles/ml serum. These data suggest that, assuming at least one binding site per protein molecule, the binding occurs to a protein of very low concentration (about 1 mg/ml) in plasma. This is consistent with the data that suggest an insignificant role of human serum albumin in the binding of LAAM and the identification of a very high molecular weight protein as the possible binding entity. The data suggest that LAAM, its metabolites, and methadone compete for the same protein binding sites and that the binding capacities of plasma for both LAAM and methadone are of the same order of magnitude. The results failed to show any cooperativity on the plasma protein binding of LAAM, its metabolites or methadone.

The effects of levo-alpha-acetylmethadol (LAAM) on locomotor activity and operant behavior were examined in rats. LAAM increased locomotor activity when given intraperitoneally (IP) at doses of 1 mg/kg and 3 mg/kg, but 10 mg/kg produced a slight decrease in motor activity over the 10-hour period. The largest increases and decreases in locomotor activity occurred 6–8 hours after administration of the drug. Other rats were trained to lever press for food pellets under a fixed-interval 90-second, fixed-ratio 10-response multiple schedule. LAAM only decreased rates of responding under the multiple schedule. Marked decreases in rates of responding under both components of the schedule occurred when LAAM was administered IP either 3 or 6 hours before the session at doses of 3 mg/kg and 10 mg/kg. The rate-decreasing effects of LAAM became greater the longer the interval between administration of the drug and initiation of the session.

The discriminative stimulus properties of l -α-acetylmethadol (LAAM), its metabolites l -α-acetyl-N-normethadol (NorLAAM) and l -α-acetyl-N,N-dinormethadol (DiNorLAAM), and methadone were evaluated in rats trained to discriminate between saline and morphine in a two-choice discrete-trial avoidance paradigm. All four compounds produced dose-related increases in the number of trials completed on the morphine-appropriate choice lever after either SC or oral administration indcating that the discriminative stimulus properties of the four compounds and morphine are qualitatively similar. LAAM and DiNorLAAM had a slow onset and long duration of action, and an oral: parenteral potency ratio of 1:3. NorLAAM had a more rapid onset and shorter duration of action and was more potent following SC administration than either LAAM or DiNorLAAM; its oral: parenteral potency ratio was 1:10. These results are consistent with evidence from other studies that the pharmacologic activity of LAAM is dependent upon the conversion of LAAM to an active metabolite, probably NorLAAM. The similarities between DiNorLAAM and LAAM suggest that the discriminative stimulus effects of the former compound are also attributable to a metabolite.

A 2.0 mg per kg oral dose of l-alpha-acetylmethadol (LAAM) administered daily to female rats prior to mating and throughout pregnancy increased ethylmorphine N-demethylase activity in liver microsomes of the dams measured 24 h after parturition. This dose of LAAM decreased maternal weight gain during gestation and increased postnatal mortality. However, 0.05 mg LAAM per kg was sufficient to produce dependence in the dams without affecting hepatic drug metabolism, gestational weight gain or neonatal mortality. The data indicate that it is not necessary to use doses of LAAM which can affect drug metabolizing enzymes in dams and increase pup mortality to maintain opioid-type physical dependence.

Adult female Sprague-Dawley rats were prepared with chronic intravenous cannulae and cortical and muscle electrodes for recording electro-encephalograms (EEG) and electromyograms (EMG), respectively. They were made physically dependent on morphine by automatic intravenous injections and then trained to lever press in order to self-administer morphine on a FR-20 schedule of reinforcement. Upon stabilization of morphine self-administration, methadone, l-alpha-acetylmethadol (LAAM), or nor-LAAM (NLAAM) was substituted for morphine. After a week in those rats self-administering methadone, LAAM or NLAAM was substituted for methadone. Continuous EEG and EMG recordings were collected. It was found that self-maintained dependence on morphine or methadone was characterized by regularly spaced single or double injections. Each morphine or methadone self-injection suppressed occurrences of rapid eye movement (REM) sleep for 30 min or more. The substitution of methadone for morphine resulted in the gradual establishment of shorter interinjection intervals within 12 h. The substitution of LAAM for morphine or methadone disrupted self-injection patterns for a day or more, and suppressed occurrences of REM sleep for several hours. LAAM self-injection patterns eventually stabilized within two to three days, and the diurnal variation in occurrences of REM sleep became relatively normal. Upon substitution of NLAAM for morphine or methadone, regularly spaced interinjection intervals were established immediately. Each NLAAM self-injection suppressed occurrences of REM sleep for about 1 h. The findings suggest that stabilization of LAAM self-administration may require accumulation of LAAM metabolites.

We have used the developing chicken to determine if ornithine decarboxylase (ODC) activity is altered in fetuses chronically exposed to the opiate N-desmethyl-l-α-acethylmethadol (NLAAM) or rendered abstinent by acute injection of naloxone (Nx). Exposure to NLAAM from day 3 of embryogenesis did not significantly change brain ODC activity in 15, 17 or 19-day-old fetuses. Acute treatment of 17-day-old fetuses with a motility suppressant dose of NLAAM did not differentially affect ODC activity in NLAAM-dependent fetuses, but an additional treatment with Nx, which precipitated withdrawal, resulted in a significant increase in ODC activity in this group. We conclude that withdrawal can alter fetal ODC activity which otherwise appears normal, even though fetuses have been chronically exposed to and dependent upon an opiate.

As time increased between drug administration and the start of experimental sessions, effects of drugs on food-maintained responding the rhesus monkeys increased to a maximum and then decreased. d-Amphetamine, ethanol, and α-l-acetylmethadol (LAAM) generally decreased high response rates in one component of a chain schedule, while very low response rates in another component were increased reliably only by ethanol. The time of peak LAAM and ethanol concentrations in blood or plasma corresponded with or overlapped the time of maximal behavioral effect, while the time of maximal behavioral effect with d-amphetamine occurred somewhat prior to the time of peak plasma-amphetamine concentration. With d-amphetamine and perhaps with ethanol, effects on operant responding were greater after 30-min pretreatment intervals than after six-hr pretreatment intervals despite higher plasma or blood concentrations at six hours than at 30 min.

A method employing solvent extraction and gas-liquid chromatography has been developed for the quantitative determination of acetylmethadol simultaneously with its two major biotransformation products, noracetylmethadol and dinoracetyl-methadol. Noracetylmethanol and dinoracetylmethanol are analyzed following their conversion to the corresponding amides. The amide structure is confirmed by the use of chemical ionization mass spectrometry and infrared spectroscopy. The method can be used to determine the concentration of acetylmethadol and these compounds in plasma samples from acetylmethadol maintenance subjects. Methanol and normethadol do not attain measurable plasma levels. Urine contains predominantly noracetylmethadol and dinoracetylmethadol. Evidence was also obtained for the urinary excretion of acetylmethadol, methadol and normethadol. A mean quantity equal to 28% of the administered dose was extreted in the urine of a 48-h dosing interval as acetylmethadol and metabolites.

Fifty of sixty original study subjects were assessed via two questionnaires and urinalysis tests between six months and one year following completion of the experimental program. Results indicate a high rate of retention in methadone/methadyl acetate treatment, and point to the need for positive social context, satisfactory interpersonal relationships, and good role functioning as concomitants to achieving drug-free status.

A quantitative GLC-mass spectrometric assay was developed for the determination of methadyl acetate in urine. The assay utilizes selective ion focusing to monitor, in a GLC effluent, the M – 15 ion generated by electron-impact ionization of methadyl acetate. Methadyl acetate- d 4 was used as an internal standard. The assay can measure 10 ng of drug/ml with about 6% precision. The curve relating the amounts of drug added to control urine versus the amounts experimentally found over a large concentration range is a straight line with a slope of 0.98 ± 0.02 and a nearly zero intercept. Assay specificity was confirmed by complete identity of the mass spectrum of methadyl acetate in the biological extract with that of the authentic material. The method was used for the urinary analysis of methadyl acetate in a rabbit given a single intravenous dose. The animal excreted less than 1% of the intact drug with a half-life of approximately 15 hr. Consequently, the long-acting characteristic of methadyl acetate must be attributed to its metabolism into active metabolites.

The behavioral effects of acute IP administration of 1-alpha-acetylmethadol, its metabolites, 1-alpha-noracetylmethadol and 1-alpha-dinoracetylmethadol, and morphine were studied in the rat using behavior controlled by a fixed-interval schedule of food reinforcement. Administraiton of all compounds produced a dose-related decrease in response rate. The metabolites were approximately three to four times the potency of the parent compound which was approximately five times the potency of morphine. Data obtained from cumulative response records suggested that the onset of effects for the metabolites was more rapid than for the parent compound.

Methadyl acetate was metabolized by microsomal preparations of rat liver to yield nor‐methadyl acetate and 6‐(dimethylamino)‐4, 4‐diphenyl‐3‐heptanol. The identification and separation of these three compounds was established by TLC, using iodoplatinate spray as a visualizing agent.