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An analytical method based on ultra-high performance supercritical fluid chromatography (UHPSFC) with photo-diode array detection (PDA) has been developed to quantify 15 sulfonamides and their N4-acetylation metabolites in serum. Under the optimized gradient elution conditions, it took only 7min to separate all 15 sulfonamides and the critical pairs of each parent drug and metabolite were completely separated. Variables affecting the UHPSFC were optimized to get a better separation. The performance of the developed method was evaluated. The UHPSFC method allowed the baseline separation and determination of 15 sulfonamides and metabolites with limit of detection ranging from 0.15 to 0.35μg/mL. Recoveries between 90.1 and 102.2% were obtained with satisfactory precision since relative standard deviations were always below 3%. The proposed method is simple, accurate, time-saving and green, it is applicable to a variety of sulfonamides detection in serum samples., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Background: Sulfonamides in combination with trimethoprim are frequently used antibiotics. They work synergistic. In infections with Pneumocystis jiroveci or Stenotrophomonas maltophilia, higher dosages are indicated than in other infections. Therapeutic drug monitoring (TDM) is warranted to assure the efficacy while limiting toxicity. Although trimethoprim in combination with sulfamethoxazole is the most common combination with established TDM target concentrations, the intravenous formulation is not suited for children because of its additives ethanol and propylene glycol to increase solubility. An alternative can be sulfametrol in combination with trimethoprim. When sulfametrol was introduced in the hospital, there was a need for a TDM method for sulfametrol., Methods: A High Pressure Liquid Chromatography-Ultraviolet (HPLC-UV) detection method for sulfametrol determination in plasma was developed and validated according to the International Conference on Harmonization guidelines. Linearity, limit of detection, lower limit of quantification, recovery, process efficiency, selectivity, within-run precision, between-run precision, and sample stability were tested., Results: All tested parameters met the required criteria. For linearity, r was 0.9948, lower limit of quantification was 10 mg/L, and limit of detection was 6 mg/L. Recovery was 100.4% and process efficiency 94.4%. Selectivity was met with no interfering peaks at the retention time of 4.2 minutes. Between-run precision and within-run precision were evaluated by replicating quality control levels, resulting in a within-run relative average standard deviation of 0.8% and a between-run relative standard deviation of 2.3%. Recovery of the samples after storing 8 days was 101.9% and recovery of already tested vials was 98.8% after 48 hours., Conclusions: In conclusion, an HPLC-UV method for sulfametrol determination in human plasma was developed and validated. The method is fast, accurate, reproducible, and has a short analysis time. It is now being used in routine TDM in our clinic.

A simple, accurate and low cost spectrophotometric method is proposed for the determination of the synthesized paracetamol derivative; 4-acetamidophenyl N'-(sulphanilamide) acetate (APSA) in biological fluids. The spectrophotometric method is based on a condensation reaction between the alcoholic solution of APSA and acidic solution of p-dimethylaminobenzaldeyde (DPMK) to generate a yellow colored product. The linear range for the determination of APSA was 1-10 µg mL(-1) with molar absorptivity of 3.6877 × 10(4) L mol(-1) cm(-1) and Sandell's sensitivity of 0.001 µg cm-2/0.001 absorbance unit. During the inter-day and intra-day analysis, the relative standard deviation for replicated determination of APSA was found to be less than 2.0% and accuracy was 99.20-101.60% and 99.10-101.30% in blood and urine samples, respectively. There was no interference with commonly used blood and urine sample. The developed spectrophotometric method was successfully applied to assess APSA in biological fluids.

In this study, 30-day-old, 14 male broiler chickens were used. Two groups, each comprising 7 animals, were established. While each animal included in the first group was administered sulfaclozine at a dose of 60 mg/kg bw by intravenous route (IV), group 2 was administered sulfaclozine at the same dose but by intracrop route (IC). In group 1, serum sulfaclozine concentrations at 0.083, 0.50, 2, 6, 24 and 72h were determined to be 99.62+/-3.31, 83.50+/-4.22, 72.68+/-5.02, 58.43+/-5.39, 38.66+/-4.04 and 13.14+/-1.64 microg/ml, respectively, via HPLC. In group 2, serum drug concentrations at 0.083, 0.50, 2, 6, 24 and 72h were determined as 4.33+/-0.45, 7.95+/-0.72, 16.46+/-2.68, 22.88+/-3.00, 16.03+/-3.53 and 5.74+/-0.98 microg/ml, respectively. Statistical analyses revealed that, of all the parameters studied, only A(1)( *), A(2)( *), alpha, beta, t(1/2)(alpha), t(1/2)(beta), MRT, Vd(area), k(12), k(21), AUC(0-->72) and AUC(0-->infinity) differed significantly between the groups (p<0.05). Compared to intravenous administration, significant increase in t(1/2)(alpha), t(1/2)(beta), MRT and Vd(area), and significant decrease in A(1)( *), A(2)( *), alpha, beta, k(12), k(21), AUC(0-->72) and AUC(0-->infinity) were observed in the group, which was administered sulfaclozine by intracrop route., (Copyright 2009 Elsevier Ltd. All rights reserved.)

The objective of the present study was to determine the acetylator status of the Bangladeshi population and to compare the findings with the acetylator status of other Asian populations. The acetylator phenotype was determined in 517 unrelated healthy Bangladeshi subjects. The phenotyping procedure was done according to Price Evans' method using the NAT2 specific probe drug--sulphadimidine. The Bangladeshi population showed a bimodal distribution of fast and slow acetylators. Of a total of 517 healthy Bangladeshi, 79.5% (n=411) were fast acetylators and the rest 20.5% (n=106) were slow acetylators. The high frequency of the fast acetylators in the population of Bangladesh was comparable to other populations in East Asia. When this acetylator status was compared with other Asian data, the Asian population showed a positive correlation between the acetylator status and the geographical longitude (r=0.919; t=7.37; p>0.001; d.f.=10). The regression line of the scatter diagram showed that the frequency of acetylating capacity increasingly occurred in the populations towards eastern Asia (regression coefficient=0.54; constant=52.36). This line was termed as the Asian fast acetylator longitude (AFAL). Thus the AFAL was able to predict the acetylator status of the Asian population by the east-west geographical longitude. The AFAL could be a useful prognosticator in the disposition for the effective and safe use of numerous drugs and xenobiotic compounds in humans.

This paper reports 1) the increase in expression of CYP1A2 in mutant Nagase analbuminemic rats (NARs), 2) the role of globulin binding of azosemide in circulating blood in its urinary excretion and hence its diuretic effects in NARs, and 3) the significantly faster renal (CL(R)) and nonrenal (CL(NR)) clearances of azosemide in NARs. Azosemide (mainly metabolized via CYP1A2 in rats), 10 mg/kg, was intravenously administered to control rats and NARs. Northern and Western blot analyses revealed that the expression of CYP1A2 increased approximately 3.5-fold in NARs as compared with control. The plasma protein binding of azosemide in control rats and NARs was 97.9 and 84.6%, respectively. In NARs, plasma protein binding (84.6%) was due to binding to alpha- (82.6%) and beta- (68.9%) globulins. In NARs, the amount of unchanged azosemide excreted in 8-h urine was significantly greater (37.7 versus 21.0% of intravenous dose) than that in control rats due to an increase in intrinsic renal active secretion of azosemide. Accordingly, the 8-h urine output was significantly greater in NARs. The area under the plasma concentration-time curve of azosemide was significantly smaller (505 versus 2790 microg. min/ml) in NARs because of markedly faster CL(R) (7.36 versus 0.772 ml/min/kg, secondary to a significant increase in urinary excretion of azosemide and intrinsic renal active secretion). Additionally, CL(NR) was significantly faster (12.4 versus 3.05 ml/min/kg, because of approximately 3.5 fold increase in CYP1A2) in NARs compared with control. Based on in vitro hepatic microsomal studies, the intrinsic M1 [a metabolite of azosemide; 5-(2-amino-4-chloro-5-sulfamoylphenyl)-tetrazole] formation clearance was significantly faster (67.0% increase) in NARs than that in control rats, and this supports significantly faster CL(NR) in NARs. Renal sensitivity to azosemide was significantly greater in NARs than in control rats with respect to 8-h urine output (385 versus 221 ml/kg) and 8-h urinary excretions of sodium, potassium, and chloride. This study supports that in NARs, binding of azosemide to alpha- and beta-globulins in circulating blood play an important role in its diuretic effects.

1. Ageing induces calcium accumulation in the vascular system. The simplest experimental way of producing high degrees of arterial calcium overload is by administration of an overdose of vitamin D(3) to rats. The aim of the present study was to evaluate the pharmacokinetics of organic anions in rats with arterial calcinosis induced by an overdose of vitamin D(3). 2. We used bromosulfophthalein (BSP) and sulfanilamide (SA) as models of organic anions with preferential biliary and renal excretion, respectively. 3. Increases in the clearance and elimination rate constant of BSP were observed in treated rats. The clearance and the elimination rate constant for SA were also increased in rats with arterial calcinosis. 4. Variations in arterial hepatic blood flow, aspartate aminotransferase activity and liver calcium accumulation were not observed in treated rats. In contrast, treated rats had a lower renal blood flow and increased renal calcium levels. 5. In summary, rats with arterial calcinosis showed an increase in total body clearance of both BSP and SA, probably associated with modifications in their metabolism and/or in organ extraction. Alterations to hepatic and renal blood flow do not account for these phenomena.

The effects of cysteine on the pharmacokinetics of azosemide were investigated after intravenous administration of drug, 10 mg/kg, to male Sprague-Dawley rats pretreated with 3-methylcholanthrene fed on 23% protein diet (control rats) and 5% protein diet without (rats with protein-calorie malnutrition, PCM) or with (rats with PCMC) oral cysteine (250 mg/kg, twice daily starting from the fourth week) for 4 weeks. After intravenous administration to rats with PCM, the metabolites of azosemide excreted in urine and recovered from gastrointestinal tract decreased significantly than those in control rats, however, the plasma concentrations, total area under plasma concentration-time curve from time zero to time infinity (AUC) and time-averaged total body clearance (CL) were not significantly different between two groups of rats. It was reported that after intravenous administration of azosemide, 10 mg/kg, to rats with PCMC without pretreatment 3-methylcholanthrene, some pharmacokinetic parameters restored fully or more than the level of control rats; the time-averaged nonrenal clearance and apparent volume of distribution at steady state were comparable to those in control rats, but the terminal half-life and mean residence time were significantly shorter, AUC was significantly smaller, and time-averaged renal clearance and CL were significantly faster than those in control rats. However, the above mentioned effects of cysteine on the pharmacokinetic parameters of azosemide in rats with PCM were not observed with pretreatment with 3-methylcholanthrene.

Pharmacokinetic profiles of therapeutic agents are altered by protein-calorie malnutrition (PCM). The current study was designed to determine the expression of hepatic cytochrome P450s in rats after protein restriction and to investigate its molecular basis. Western blot analysis revealed that rats with protein restriction for 4 weeks exhibited marked suppression in the hepatic P450 1A2, 2C11, 2E1, and 3A1/2 levels. Northern blot analysis showed that hepatic P450 1A2, 2C11, and 3A1/2 mRNAs were significantly decreased in the state of PCM. The P450 2E1 mRNA level was slightly decreased in PCM rats, suggesting the possibility that expression of P450 2E1 affected by PCM might result from the transcriptional and/or posttranscriptional regulation. PCM-induced changes in most P450 expression completely or partially returned to control levels by a week of cysteine supplementation. Cysteine also prevented decreases in P450 1A2, 2C11, 2E1, and 3A1/2 mRNA levels by PCM. Methionine was minimally active in restoring the P450 expression. A metabolic change in hepatic ethoxyresorufin dealkylase activity in PCM rats was consistent with the P450 apoprotein and mRNA levels. Although the plasma concentrations of azosemide, a loop diuretic, primarily metabolized by cytochrome P450 1A, increased in protein-deprived rats, cysteine supplementation significantly reduced the increased plasma concentrations of the drug. The altered pharmacokinetic parameters of azosemide in PCM rats returned to those of control after cysteine supplementation, corroborating the conclusion that cysteine was effective in restoring cytochrome P450 expression and metabolic activities., (Copyright 1999 Academic Press.)

Gender differences in pharmacokinetics and pharmacodynamics of azosemide were evaluated after intravenous, 10 mg kg(-1), and oral, 10 mg kg(-1), administration to male and female rats. After intravenous administration to male rats, the percentages of intravenous dose of azosemide recovered from entire gastrointestinal tract at 24 h (13.2 versus 3.93%) was significantly greater than those in female rats. In male rats, the nonrenal clearance of azosemide tended (p<0.066) to be faster and kidney weight tended (p<0.068) to be greater than those in female rats. After oral administration of azosemide to male rats, the 8-h urinary excretion of potassium (0.395 versus 0.766 mmol g(-1) kidney) and 8-h kaluretic efficiency (55.9 versus 284 mmol mg(-1)) decreased significantly compared with female rats., (Copyright 1999 John Wiley & Sons, Ltd.)

The pharmacokinetic and pharmacodynamic differences of azosemide were investigated after intravenous (i.v.) and oral administration of azosemide, 10 mg kg-1, to the control and uranyl nitrate-induced acute renal failure (U-ARF) rats. After IV administration, the plasma concentrations of azosemide were significantly higher in the U-ARF rats and this resulted in a significant increase in AUC (2520 versus 3680 micrograms min mL-1) and significant decrease in Cl (3.96 versus 2.72 mL min-1 kg-1) of azosemide. The significant decrease in Cl in the U-ARF rats was due to the significant decrease in Clr of azosemide (1.55 versus 0.00913 mL min-1 kg-1) due to the decrease in kidney function in the U-ARF rats. After IV administration, the urine output (38.5 versus 8.45 mL 100 g-1 body weight) and urinary excretion of sodium (4.60 versus 0.420 mmol 100 g-1 body weight) decreased significantly in the U-ARF rats. After oral administration, the AUC0-8 h of azosemide decreased significantly (215 versus 135 micrograms min mL-1) in the U-ARF rats possibly due to the decreased GI absorption of azosemide. After oral administration, the 24-h urine output decreased considerably (16.1 versus 11.2 mL 100 g-1 body weight, p < 0.098) and the 24-h urinary excretion of sodium (1.74 versus 0.777 mmol 100 g-1 body weight) decreased significantly in the U-ARF rats. The i.v. and oral doses of azosemide needed to be modified in the acute renal failure patients if the present rat data could be extrapolated to humans.

Since considerable first-pass effects of azosemide have been reported after oral administration of the drug to rats and man, first-pass effects of azosemide were evaluated after intravenous, intraportal and oral administration, and intraduodenal instillation of the drug, to rats. The total body clearances of azosemide after intravenous (5 mg kg-1) and intraportal (5 and 10 mg kg-1) administration of the drug to rats were considerably smaller than the cardiac output of rats suggesting that the lung or heart first-pass effect (or both) of azosemide after oral administration of the drug to rats was negligible. The total area under the plasma concentration-time curve from time zero to time infinity (AUC) after intraportal administration (5 mg kg-1) of the drug was significantly lower than that after intravenous administration (5 mg kg-1) of the drug (1000 vs 1270 micrograms min mL-1) suggesting that the liver first-pass effect of azosemide was approximately 20% in rats. The AUC from time 0 to 8 h (AUC0-8 h) after oral administration (5 mg kg-1) of the drug was considerably smaller than that after intraportal administration (5 mg kg-1) of the drug (27.1 vs 1580 micrograms min mL-1) suggesting that there are considerable gastrointestinal first-pass effects of azosemide after oral administration of azosemide to rats. Although the AUC0-8 h after oral administration (5 mg kg-1) of azosemide was approximately 15% lower than that after intraduodenal instillation (5 mg kg-1) of the drug (27.1 vs 32.0 micrograms min mL-1), the difference was not significant, suggesting that the gastric first-pass effect of azosemide was not considerable in rats. Azosemide was stable in human gastric juices and pH solutions ranging from 2 to 13. Almost complete absorption of azosemide from whole gastrointestinal tract was observed after oral administration of the drug to rats. The above data indicated that most of the orally administered azosemide disappeared (mainly due to metabolism) following intestinal first-pass in rats.

Healthy adult male desert sheep were experimentally infected with Fasciola gigantica, to investigate the influence of experimental fasciolasis on the pharmacokinetics of antipyrine and sulphadimidine. Each animal received 500 metacercariae orally. The experimental infection was confirmed histologically, by detection of Fasciola eggs in faeces and by measuring the activities of the enzymes sorbitol dehydrogenase (SD), glutamate dehydrogenase (GD) and aspartate aminotransferase (AST) in plasma during the course of the disease. Changes in the pharmacokinetics of antipyrine and sulphadimidine were reported in the experimentally infected animals. Significant prolongation of antipyrine half life was observed 16 weeks after infection. The half-life of sulphadimidine was also significantly prolonged 5, 9 and 16 weeks after infection. Clearance of the sulphonamide was decreased significantly 5 and 9 weeks after infection and it regained its pre-infection value 16 weeks after infection.

The need for fast and efficient separations of complex samples such as pharmaceuticals and biologicals led to the development of fast, efficient, and reproducible 3.5 microns columns. Separations using 3.5 microns column are 30-50% faster at equal plate-count compared to 5 microns columns. The results show that the 3.5 microns columns (100 mm length) give the same efficiency and resolution of drug impurities as the 5 microns columns (150 mm length). For many analytical methods, switching to 3.5 microns columns saves time and reduces costs. Separation methodologies using 5 microns columns are easily modified to accommodate 3.5 microns columns of the same chemistry because efficiency, resolution and sensitivity remain the same. It is shown that 3.5 microns columns have lifetimes comparable to 5 microns columns of the same brand.

Purpose: Chloroquinoxaline sulfonamide (CQS) was one of the first agents identified by the human tumor colony-forming assay (HTCFA) as possessing antitumor activity in non-small-cell lung cancer (NSCLC). Prior phase I studies had suggested that plasma concentrations equivalent to those showing efficacy in the HTCFA could be reliably attained in humans. This phase II study assessed the antitumor activity of CQS while using an adaptive control pharmacokinetic modelling system to attain targeted plasma levels of this novel compound., Methods: A group of 20 patients with stage III or IV NSCLC received CQS as a 1-h weekly infusion at an initial dose of 2 g/m2. In all patients, 24-h plasma concentrations of CQS were measured. Patients with levels < 100 micrograms/ml had dose increases determined by their 24-h levels and pharmacokinetic parameters obtained from two prior phase I trials of this agent. These individuals had 24-h CQS levels repeated after their second weeks' treatment and doses were readjusted if the target concentration was not reached. Antitumor response assessment was made every 6 weeks., Results: Of the 20 patients, 18 attained the target plasma concentration, and 16 of these achieved this initially or with just one dose adjustment. No major objective antitumor responses were observed (major response rate 0%, 95% CI 0-17%). CQS was well tolerated with hypoglycemia being the most clinically significant toxicity., Conclusions: When given on this schedule CQS is inactive in NSCLC despite the fact that the target concentration was achieved in 90% of patients. The ability of the HTCFA to identify active agents remains unproved.

Azosemide, 5, 10, 20, and 30 mg/kg, was administered both intravenously and orally to determine the pharmacokinetics and pharmacodynamics of azosemide in rats (n = 7-12). The absorption of azosemide from various segments of GI tract and the reasons for the appearance of multiple peaks in plasma concentrations of azosemide after oral administration were also investigated. After intravenous (iv) dose, the pharmacokinetic parameters of azosemide such as t1/2. MRT, VSS, CL, CLR, and CLNR were found to be dose-dependent in the dose ranges studied. The percentages of the iv dose excreted in 8-hr urine as azosemide, MI (a metabolite of azosemide), glucuronide of azosemide, and glucuronide of MI-expressed in terms of azosemide-were also dose-dependent in the dose ranges studied. The data above suggest saturable metabolism of azosemide in rats. The measurements taken after the iv administrations such as the 8 hr urine output, the total amount of sodium and chloride excreted in 8-hr urine per 100 g body weight, and diuretic, natriuretic, kaluretic, and chloruretic efficiencies were also shown to be dose-dependent. However, the total amount of potassium excreted in 8-hr urine per 100 g body weight was dose-independent. Similar dose-dependency was also observed following oral administration. Azosemide was absorbed from all regions of GI tract studied and approximately 93.5, 79.1, 86.1, and 71.5% of the doses (5, 10, 20, and 30 mg/kg, respectively) were absorbed between 1 and 24 hr after oral administration. The appearance of multiple peaks after oral administration is suspected to be due mainly to the gastric emptying pattern. The percentages of azosemide absorbed from the GI tract as unchanged azosemide for up to 24 hr after oral doses of 5, 10, 20, and 30 mg/kg were significantly different with doses (decreased with increasing doses), suggesting that the problem of azosemide precipitating in acidic gastric juices or dissolution may have at least partially influenced the absorption of azosemide after oral administration.

Healthy gilts and market-ready hogs were administered a single intramuscular (IM) injection of Borgal, a commercial formulation of trimethoprim-sulfadoxine (TMP-SDX), once or twice daily. The objectives were to determine if a newly-developed high-performance liquid chromatographic (HPLC) method would be suitable for measuring the residual concentrations of TMP in the plasma of these live animals, and to determine if the administration of this veterinary drug would leave measurable residues in their plasma and tissues at slaughter. Plasma and tissue concentrations of SDX and TMP from these animals were determined over a period of 14 d using thin-layer chromatography/densitometry (TLCD), and the newly-developed HPLC method, respectively. The lowest detectable limit (LDL) for SDX in plasma and tissue was 20 ppb by TLCD. The HPLC method had a LDL of 5 ppb for TMP in plasma and tissue. Both methods were then used to provide baseline data on the absorption and depletion of TMP and SDX from these healthy animals. It was observed that both TMP and SDX were readily absorbed into the blood and tissues, but TMP was eliminated much faster than SDX. No TMP residues were detected in the plasma of any of the gilts at and beyond 21 h after drug administration. Also, no TMP residues were detected in the plasma of any of the market-ready hogs 24 h after drug administration at either the label dose or twice the label dose. Sulfadoxine residues at concentrations above the maximum residue limit (MRL) of 100 ppb were, however, detected in the plasma, muscle, kidney, liver, and injection sites of hogs slaughtered 1 and 3 d after a single IM administration at the label dose. Although SDX residues were still detectable in the lungs, kidney, liver and plasma of some hogs 10 d after administration of the label dose and twice the label dose, these were below the MRL. Postmortem examination revealed necrosis and inflammation at the injection sites, but no visible deposits of the injected drug.

The bioavailability of two different forms of medicated feed containing 2000 mg sulfadimidine (SDM) per kg was determined in three groups of eight piglets. In the first group, pharmacokinetic parameters of SDM were determined after a single intravenous dose of 10 mg/kg body weight and after single oral doses of 45 mg/kg body weight ingested either as an oleus solution sprayed directly onto the feed pellets ready for use (SPR) or as a commercially available premix incorporated into the feed before pelletising (PMX). After the single intravenous administration, the mean +/- SD of the volume of distribution was 0.34 +/- 0.05 l/kg, the total body clearance 0.37 +/- 0.07 ml/min.kg, the mean residence time 15.5 +/- 2.5 h, and the elimination half-life 11.1 +/- 2.0 h. Although no statistical significance existed, a single meal with PMX was associated with slightly higher mean values for the maximum serum concentration (Cmax), the time to reach Cmax, and the bioavailability (52.98 +/- 6.60 micrograms/ml, 6.8 +/- 1.1 h, 59.7 +/- 12.1%, respectively, vs. 40.04 +/- 13.19 micrograms/ml, 6.0 +/- 1.4 h, 49.0 +/- 18.6 for SPR). The remaining two groups of piglets received medicated feed with either SPR or PMX during a 3-day period both with restrictive (twice-daily) or ad libitum feeding according to a cross-over design. In all four cases, potentially efficacious plasma SDM concentrations between 50 and 150 micrograms/ml were obtained within 24 h after initiation of the treatment. With PMX, plasma concentrations tended to be higher than with SPR with both feeding regimens. Ad libitum feeding was associated with a significantly higher food intake and hence a higher SDM intake resulting in higher plasma concentrations. Additionally, plasma concentrations were more constant over time with ad libitum feeding whereas they declined considerably between meals in restrictively fed animals. In vitro dissolution tests of the two types of medicated feed revealed that SDM was rapidly released from SPR (58% within 15 min) and that SDM release from PMX was markedly slower (3% within 15 min). Despite the relatively slow rate of in vitro dissolution, in vivo absorption of SDM was satisfactory. It is concluded that both forms of SDM medicated feed may be considered bioequivalent and potentially efficacious in piglets.

Stability of azosemide after incubation in various pH solutions, human plasma, human gastric juice, and rat liver homogenates, metabolism of azosemide after incubation in 9000 g supernatant fraction of various rat tissue homogenates in the presence of NADPH, tissue distribution of azosemide and M1 after intravenous (i.v.) administration of azosemide, 20 mg kg-1, to rats, and blood partition of azosemide between plasma and blood cells from rabbit blood were studied. Azosemide seemed to be stable for up to 48 h incubation in various pH solutions ranging from two to 13 at an azosemide concentration of 10 micrograms mL-1; more than 93.4% of azosemide was recovered, and a metabolite of azosemide, M1, was not detected. However, the drug was unstable in pH1 solution: 75.8% of azosemide was recovered and 2.16 micrograms mL-1 of M1 (expressed in terms of azosemide) was formed after 48 h incubation in pH 1 solution at an azosemide concentration of 10 micrograms mL-1. Azosemide was stable in both human plasma and rat liver homogenates for up to 24 h incubation at an azosemide concentration of 1 microgram mL-1, and in human gastric juice for up to 4 h incubation at an azosemide concentration of 10 micrograms mL-1. However, all rat tissues studied had metabolic activity for azosemide in the presence of NADPH, with heart having a considerable metabolic activity: approximately 22% of azosemide disappeared and 9.32 micrograms of M1 was formed per gram of heart (expressed in terms of azosemide) after 30 min incubation of 50 micrograms of azosemide in 9000 g supernatant fraction of heart homogenates. The tissue to plasma ratios of azosemide (T/P) were greater than unity only in the liver (1.26) and kidney (1.74); however, M1 showed high affinity for all tissues studied except the brain and spleen when each tissue was collected at 30 min after i.v. administration of azosemide to rats. The equilibrium plasma to blood cell concentration ratios of azosemide were independent of azosemide blood concentrations: the values were 2.78-4.25 at azosemide blood concentrations of 1, 10, and 20 micrograms mL-1 in three rabbits. There was negligible 'blood storage effect' of azosemide, especially at low blood concentrations of azosemide, such as 1 and 10 micrograms mL-1.

High-performance liquid chromatographic methods were developed for the determination of azosemide and its metabolite, M1, in human plasma and urine and rabbit blood and tissue homogenates. The methods involved deproteinization of the biological samples: 2.5 volumes of acetonitrile were used for the determination of azosemide and 1 volume of saturated Ba(OH)2 and ZnSO4 for that of M1. A 50-microliters aliquot of the supernatant was injected onto a C18 reversed-phase column in each instance. The mobile phases employed were 0.03 M phosphoric acid-acetonitrile (50:40, v/v) for azosemide and 0.03 M phosphoric acid/0.2 M acetic acid-acetonitrile (83:17, v/v) for M1. The flow-rate was 1.5 ml/min in both instances. The column effluent was monitored by ultraviolet detection at 240 and 236 nm for azosemide and M1, respectively. The retention times for azosemide and M1 were 6.0 and 8.3 min, respectively. The detection limits for both azosemide and M1 in both human plasma and urine were 50 ng/ml. The coefficients of variation of the assay were generally low (below 11.0%) for plasma, urine, blood and tissue homogenates. No interferences from endogenous substances or other diuretics tested were observed.

The pharmacokinetics of azosemide were evaluated simultaneously using both arterial and venous plasma data in six rabbits after a rapid 5 s intravenous bolus dosing. Initial arterial to venous ratios at 5 s after injection were the highest with values of 81.1, 67.3, 58.7, 530, 2660, and 10.5 for rabbits 1-6, respectively. Both curves decayed, paralleling each other at the terminal phase, with the venous levels higher than the arterial levels by 15.3, 31.9, 34.1, 40.7, 30.5, and 16.5% for rabbits 1-6, respectively. An exponential term with a negative coefficient was used to account for the short and steep rising phase of venous plasma levels after injection. Detailed analysis showed significant differences in various pharmacokinetic parameters, such as initial volume of distribution, apparent volume of distribution at steady state, and mean residence time based on arterial or venous data. A plot of 1/Q (urine flow rate) versus 1/CLR (renal clearance) of azosemide yielded a straight line in six rabbits, indicating that the CLR of azosemide is urine flow dependent in rabbits.

In search of reliable genetic markers of protracted and complicated pneumonia, the authors studied blood groups, haptoglobin phenotype, sulfadimisine acetylation. These markers proved essential for predicting pneumonia course and prognosis.

To investigate regulation of the Na-K-Cl cotransport system in the rectal gland of the dogfish shark Squalus acanthias, we examined binding of the loop diuretic [3H]benzmetanide to the intact gland. Glands were perfused with a shark Ringer solution, either in a basal state or stimulated with vasoactive intestinal peptide (VIP). [3H]benzmetanide was added to the perfusion solution for the last 25 min of perfusion, after which the gland was homogenized and the amount of bound [3H]benzmetanide was determined in the membrane fraction. Most of the membrane-associated [3H]-benzmetanide appeared to be associated with the Na-K-Cl cotransporter as judged by the dissociation rates at 0 degree C and 20 degrees C, by labeling with a photosensitive analogue, and by continued association of [3H]benzmetanide with membrane protein on solubilization. With the use of [3H]4-benzoyl-5-sulfamoyl-3-(3- thenyloxy)benzoic acid, a photosensitive analogue of benzmetanide, a 200-kDa protein was selectively labeled on exposure to ultraviolet light. It was also possible to detect [3H]-benzmetanide binding during the perfusion period as an arterial-venous difference, thereby providing a time course of the binding process. In comparing two groups of five glands each, VIP stimulated NaCl secretion 20-fold and [3H]benzmetanide binding 16-fold, providing strong evidence that the Na-K-Cl cotransport system is activated as part of the process of stimulation of secretion. The VIP-stimulated increase in [3H]benzmetanide binding was completely inhibited when Ba was added to the perfusate to block K channel-mediated K exit across the basolateral membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Amino-4-chloro-m-benzenedisulfonamide (ACBS) is a metabolite of hydrochlorothiazide. We reported that the ACBS concentration in erythrocytes was higher than in plasma in a patient. Therefore the binding of ACBS to rabbit erythrocyte was studied. The Scatchard plot showed the nonlinear plot and the horizontal asymptote. Curvature in this plot indicated the existence of 2 classes of binding. One class was at a specific site, probably at carbonic anhydrase. Chromatographic data seemed to support the possibility.

We examined 122 patients with inflammatory bowel disease treated with salicylazosulfapyridine. Forty-two (34.5%) had adverse effects that led to discontinuation of therapy in 14 (11.5%). In 33 patients the effects appeared to be dose dependent. The plasma sulfapyridine levels in patients exhibiting gastrointestinal side effects were significantly higher than in patients with no adverse effects (41.0 +/- 20.3 and 23.8 +/- 14.8 micrograms/ml respectively, P less than 0.001). Plasma sulfapyridine levels were significantly higher in slow than in fast acetylators (31.5 +/- 17.1 vs. 22.2 +/- 17.1 micrograms/ml). Slow acetylators had three times as many side effects as fast acetylators; however this difference was not statistically significant.

The effect of molecular structure on the drug disposition and protein binding in plasma, the urinary recovery, and the renal clearance of sulphamerazine (SMR), sulphadiazine (SDZ), and sulphadimidine (SDM) and their N4-acetyl and hydroxy derivatives were studied in pigs. Following IV administration of SDM, SMR and SDZ, their mean elimination half-lives were 12.4 h, 4.3 h and 4.9 h respectively. The plasma concentrations of parent sulphonamide were higher than those of the metabolites, and ran parallel. The acetylated derivatives were the main metabolites; traces of 6-hydroxymethylsulphamerazine and 4-hydroxysulphadiazine were detected in plasma. The urine recovery data showed that in pigs acetylation is the major elimination pathway of SDM, SMR and SDZ; hydroxylation became more important in case of SMR (6-hydroxymethyl and 4-hydroxy derivatives) and SDZ (4-hydroxy derivatives) than in SDM. In pigs methyl substitution of the pyrimidine side chain decreased the renal clearance of the parent drug and made the parent compound less accessible for hydroxylation. Acetylation and hydroxylation speeded up drug elimination, because their renal clearance values were higher than those of the parent drug.

For determination of the sulphapyridine level there were used 83 sera of 57 patients with Crohn's disease or ulcerative colitis which were treated with salazosulphapyridine. In 22,8 percent there was a sulphapyridine level higher than the therapeutic range of the whole sulphapyridine of 20-50 micrograms/ml. The serum levels are below this range frequently. Sulphonamide containing drugs yield too high values. Generally no sulphapyridine is shown in the serum because of the missing splitting of the salazosulphapyridine in patients with colectomie. Low serum values are found at low patient-compliance. In diarrhoea sulphapyridine levels in the serum are decreased. Determination of the sulphapyridine level is suitable: a) for recognition of too high serum levels and therefore for prevention of side effects b) to make sure that the therapeutic range is reached.

Fifteen children followed as outpatients with chronic inflammatory disease of the colon were given sulfasalazine in doses from 1 to 4 gm/day (22 to 68 mg/kg, or 0.69 to 2.33 gm/m2). No correlation was found between the dose/m2 administered and the total serum sulfapyridine levels. However, 11 of 15 patients achieved SP levels greater than or equal to 17 micrograms/ml, a level approximating that reputedly associated with therapeutic efficacy. Patients who were either slow acetylators or slow hydroxylators of sulfapyridine had total SP levels significantly higher than patients who were both rapid acetylators and hydroxylators (20.0 +/- 1.2 vs 14.6 +/- 1.6). Total SP serum levels were not correlated with the activity of the disease. No toxic levels (greater than 50 micrograms/ml of SP) were encountered. We conclude that a dose of SASP in the range of 1.5 to 2.0 gm/m2 can be safely administered to children and is usually associated with serum SP levels considered in the therapeutic range. Although one-third of children are both rapid acetylators and hydroxylators and will have somewhat lower SP levels, the routine monitoring of SASP therapy with SP levels is not necessary for management of disease.

Lidaprim, a new bactericidal combination of trimethoprim and sulfametrol, was administered to 20 patients of a paediatric surgical ward over a period of 7 or more days. Analytic determination of plasma and urine concentrations of the chemotherapeutic agent showed homogeneous drug levels at the chosen dosage. No cumulation was observed. Drug tolerance was excellent. Only one patient developed urticaria when the substance was given together with penicillin, but it was not necessary to stop medication in this case.

Inadequate therapeutic results in the treatment of bacterial infections in patients with Cystic Fibrosis prompted a reevaluation of pharmacokinetic parameters of orally and parenterally administered drugs in these patients. Gentamicin, Azlocillin and Ticarcillin are eliminated faster in patients with Cystic Fibrosis. Serum concentrations show a rapid decrease over 60 to 90 minutes and surpass MIC values of Pseudomonas isolates for a maximum of only 60 minutes. 70% to 90% of the administered amount of drug is eliminated within two hours in the urine. Concomitantly determined clearance rates for creatinine didn't show abnormalities, however they pointed towards an additional tubular secretion of Gentamicin which is not seen in healthy controls. Cephalexin, Epicillin and both components of Cotrimoxazol show a delay in oral absorption. The renal elimination of Cephalexin and Trimethoprim is unaltered, but the excretion of Epicillin and Sulfametrol is enhanced again. This is seen by a delay and decrease in the maximal serum concentration (Cmax), but increased urine recovery. Doubling of the dose of gentamicin administered as i. v. infusion over 45 to 60 minutes results in smooth serum curve, the MIC values of most encountered organisms are surpassed for 3 hours and more. The clinical applicability of this recommendation however awaits further investigations concerning efficacy and safety.

For the determination of the plasma concentration profiles of pyrimethamine and sulfadoxine after the administration of 1 tablet of Fansidar, highly specific analytical methods are needed as the pyrimethamine concentration is low (0.2 - 0.02 mg/litre) and the concentration ratio of the two components in the plasma is high (> 1: 500). The microbiological method described in this paper fulfils these requirements for high specificity and sensitivity (the sensitivity limit for sulfadoxine is 1 mg/litre and for pyrimethamine is 0.013 mg/litre).Pharmacokinetic data were evaluated for 14 volunteers after administration of 1 tablet of Fansidar, and a computer simulation of multiple dosing (1 tablet per week) was performed.

Pharmacokinetic parameters of the long-term sulfanilamide Sulfaclomid (4-[4-aminobenzensulphonamido]2,6-dimethyl-5-chlorpyrimidine) were determined in 25 female subjects. Both the elimination half-life of Sulfaclomid in the serum and the maximum acetylation rate in the urine are genetically determined. They show a polymodal behavior. The half-life is unrelated to the protein binding, which shows considerable individual differences in the therapeutic relevant range of about 200 microgram/ml serum. This confirms the human pharmacological postulate according to pharmacokinetical dosage schedules including genetic factors. An individual therapy service is necessary in certain drugs and in highly endangered groups of patients.

Fansimef is a new antimalarial combination containing pyrimethamine, sulfadoxine and mefloquine in the weight proportions 1 + 20 + 10. It has been designed to fight plasmodia resistant to the presently used antimalarial drugs and to counter the development of new resistant forms of the parasites. In the present study tablets containing 25 mg pyrimethamine, 500 mg sulfadoxine and 250 mg mefloquine were used. Six Brazilian volunteers received a loading dose of 2 tablets followed by 20 maintenance doses of 1 tablet at a dosage interval of 7 days. The pharmacokinetic evaluation of each of the three components was based on the assumption of an open linear two-compartment model. After the last maintenance dose the following kinetic parameters were determined for pyrimethamine, sulfadoxine and mefloquine, respectively: elimination half-life = 123, 179 and 550 h; volume of distribution in the postdistributive phase = 2.5, 0.15 and 18.6 1 X kg-1, and total systemic clearance = 14.0, 0.64 and 24.0 ml X h-1 X kg-1. All these values agree fairly well with those measured in previous single-dose kinetic studies. At steady state, Cmin values of each of the three components generally showed small variations. No unexpected accumulation of any of the three components was observed, indicating that induction or inhibition of metabolic enzymes did not occur during the trial.

Half-life of sulfalen, a new antibacterial drug, with the biotransformation, performed by means of microsomal acetyltransferase, has been studied in 53 individuals of Moscow Russian population. The absence of sex dimorphism for the trait studied is demonstrated. Distribution of individuals according to values of the pharmacokinetic parameter mentioned within the population is bimodal with the correlation of phenotypic frequencies of "rapid" and "slow" inactivators--72 and 28%. Possible causes of discrepancies between the observed sulfalen inactivator frequencies and similar data on isoniazid are discussed.

Comparative study of sulfamonomethoxin pharmacokinetics in the man given the drug per os or parenterally in the form of methylglucaminate showed that the latter favours higher blood concentrations of the drug 12 hours following injection. Sulfamonomethoxinmeglumin is absorbed more rapidly and has a greater bioavailability. The drug is mainly excreted with urine, more than a half being excreted in an acetylated form. It is recommended that the initial and maintenance doses be not less than 1000 and 500 mg for both dosage forms respectively. The interval between sulfanilamide administrations should not exceed 24 hours.

Estimations of the serum level of sulfapyridine in 21 patients suffering from colitis ulcerosa or Crohn's disease, have been carried out. Nearly 50 per cent of all the serum levels were within the therapeutic range between 20 and 50 micrograms/ml. Some factors influencing the sulfasalazine metabolism are mentioned. The estimation of the serum levels of sulfapyridine is a suitable method for supervision of patients receiving treatment with sulfasalazine.

A specific, sensitive high-performance liquid chromatographic method is described for sulfaquinoxaline (I) and its major metabolite, the N4-acetyl metabolite (II), in biological fluids. Detection limits for I and II were 0.25 and 0.50 micrograms/mL in plasma and 0.10 and 0.20 micrograms/mL in urine, respectively. The pharmacokinetics of sulfaquinoxaline and its metabolite were studied in New Zealand White rabbits after individual doses of 50 mg/kg of sulfaquinoxaline and its metabolite were administered intravenously. Mean (+/- SD) plasma half-lives were 12.7 (8.0) h for sulfaquinoxaline and 15.4 (3.5) h for the metabolite. After administration of the N-acetyl metabolite sulfaquinoxaline appeared in the plasma and urine indicating that deacetylation had occurred. The repercussions of this observation are briefly discussed with respect to two rabbits in which plasma analyses and complete urine collections were made. As sulfaquinoxaline is administered prophylactically to rabbits by some breeders, it is recommended that investigators allow a washout period of about one week after receipt of the animals.