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Otilonium bromide (OB) is a drug with spasmolytic activity belonging to quaternary ammonium derivatives and extensively used to treat patients affected by the Irritable Bowel Syndrome (IBS). Thanks to its peculiar pharmacokinetic, OB concentrates in the large bowel wall and acts locally. From the pharmacodynamics point of view, OB is able to inhibit i) the main patterns of human colonic motility in vitro; ii) the contractility caused by excitatory motor neurons stimulation (pre-synaptic action) and iii) the contractility caused by the direct action of excitatory neurotransmitters (post-synaptic action). Interestingly, these effects derive from a complex interaction between the drug and several cellular targets. The main action consists in the blockade of Ca2+ entry through L-type Ca2+ channels and interference with intracytoplasmatic Ca2+ mobilization necessary for SMC contraction, thus preventing excessive bowel contractions and abdominal cramps. Further, OB blocks the T-type Ca2+ channels and interferes with the muscarinic responses; it interacts, directly or indirectly, with the tachykinin receptors on SMC and on primary afferent neurons whose combined effects may result in the reduction of motility and abdominal pain. In summary, a revision of this complex picture of OB activity could help to better address its therapeutic use.

Oxidative stress has been linked to endothelial dysfunction and angiotensin II stimulates the reactive oxygen species production contributing to several cardiovascular diseases. We have studied the chain of events induced by angiotensin-converting-enzyme (ACE) activation in vascular umbilical vein endothelial cells (HUVECs) by using an ACE inhibitor such as zofenoprilat.

Objective This study examined the combined effect of nebivolol (NEB) and hydrochlorothiazide (HCTZ) on cardiovascular function in spontaneously hypertensive rats (SHR).Methods SHR normotensive male rats were randomly assigned to five groups (n= 8 per group): (i) SHR control group; (ii) NEB 2 mg/kg per day group; (iii) HCTZ 10 mg/kg per day group; (iv) NEB 2 mg/kg per day + HCTZ 10 mg/kg per day group; (v) Eight age-matched Wistar-Kyoto normotensive male rats served as the control group. All groups were treated orally for 8 weeks.Results The combination of NEB + HCTZ synergistically reduced systolic blood pressure and heart rate compared with either monotherapy. HCTZ increased water intake, which is a sign of diuresis. NEB reduced plasma angiotensin II concentration, which was increased in SHR and after HCTZ treatment. NEB + HCTZ increased plasma nitric oxide (NO) concentration and NO synthase activity, which were both reduced in SHR. NEB + HCTZ normalized femoral arterial vasorelaxation induced by acetylcholine, which was impaired in SHR.Conclusions The combination of NEB + HCTZ provided a number of beneficial and additive effects due to the synergistic characteristics of both drugs, in an experimental rat model of hypertension.

Tachykinins (TKs) are small peptides widely distributed in the central and peripheral nervous systems where they act as neurotransmitters. Potent and selective TKs antagonists have been developed in the last 20 years and many efforts have been made to prove their efficacy in the treatment of various diseases. Herein the most prominent results in the clinical development are reported and discussed. For aprepitant, the only compound of this class to have been launched to date, results of clinical studies and postmarketing cost-effectiveness data for the treatment of chemotherapy-induced emesis are discussed. The field is still well active, as currently proof-of-concept studies for indications initially missed (i.e., depression) are ongoing and new targets are under investigation.

D/L-Nebivolol is a lypophilic β1-adrenergic antagonist which is devoid of intrinsic sympathomimetic activity and can increase nitric oxide (NO) bioavailability with its subsequent vasodilating properties. The purpose of the present work was to assess the effect of long-term nebivolol administration on both renal damage and endothelial dysfunction induced by renal mass reduction (RMR) in rats. Atenolol, which does not increase NO bioavailability, was included in the study as a comparative β-adrenoceptor antagonist.

The present study investigates the effects of chronic administration of ACEIs (angiotensin-converting-enzyme inhibitors; either zofenopril or enalapril) in combination with a diruetic (hydrochlorothiazide) on BP (blood pressure) increase and renal injury induced by L-NAME (NG-nitro-L-arginine methyl ester), an inhibitor of NO (nitric oxide) synthesis. Rats were untreated or received L-NAME alone, L-NAME+zofenopril+hydrochlorothiazide or L-NAME+enalapril+hydrochlorothiazide for 8 weeks. L-NAME treatment resulted in marked elevation in BP and mortality. Treatment with either ACEI and diuretic prevented the increase in BP induced by L-NAME, reduced the death rate and improved excretory parameters. Renal injury in the L-NAME group was severe, but, in the groups treated with either ACEI and diuretic, glomerular and tubulointerstitial lesions were not observed and the intensity, number and size of vessels affected was reduced. However, the efficacy of zofenopril+diuretic was superior to that of enalapril+diuretic in reducing vascular alterations. Oxidative stress indices and the expression of NO synthase and nitrotyrosine were normalized by the treatments. In conclusion, the combined treatment of zofenopril or enalapril with hydrochlorothiazide completely prevented the development of arterial hypertension induced by L-NAME. Renal morphological and functional alterations in the hypertensive animals were also almost completely normalized, but the treatment with zofenopril+diuretic produced a more complete organ protection. The protective effect is related to an activation of endothelial NO synthase expression and to a normalization of the oxidative stress parameters due to the inhibition of angiotensin II.

A wide distribution of tachykinin-containing projections of capsaicin-sensitive primary afferent neurons is present in the peripheral organs of respiratory, gastrointestinal and genitourinary systems. Tachykinins, along with calcitonin gene-related peptide (CGRP) and other neuropeptides, can be released by adequate stimuli having pathological rather than physiological relevance. In most cases these stimuli are represented by chemical irritants penetrating through the respiratory tree or alimentary channel to the body, or being removed through the urinary system. Tachykinins produce in the visceral organs part of the responses obtained at somatic level by antidromic activation of capsaicin-sensitive nerve terminals and known as “neurogenic inflammation” that is, increase in vascular permeability and plasma protein leakage followed by oedema. In addition tachykinins produce at visceral level smooth muscle contraction, neuronal stimulation, mucus secretion and recruitment / activation of immune cells. The physiological significance of these effects is to afford protection toward chemical irritants or noxious stimuli by facilitating their removal from the body. Nonetheless, a large body of preclinical evidence exists indicating that tachykinins participate in the genesis and/or maintenance of symptoms accompanying various human diseases, such as asthma / bronchial hyperreactivity, cystitis of various aetiologies, inflammatory bowel diseases and irritable bowel syndrome. Tachykinin receptor antagonists, proved capable of preventing/reducing tachykinin-mediated effects in experimental animal models of these pathologies, are expected to afford therapeutically relevant effects in humans.

The aim of this study was to determine the plasma levels and the tissue distribution of otilonium bromide, measured as total radioactivity, after oral administration of 2 mg/kg of 14C-labeled drug to rats. Radioactivity levels were very low in the plasma (ranging from 2.7 ng Eq/ml at 1.5 h to 0.6 ng Eq/ml at 24 h) as compared with those found in the gastrointestinal (GI) tract, indicating negligible systemic otilonium bromide absorption. Results from both quantitative radioluminography of whole body tissue distribution and radioassay of dissected parts of the GI tract carried out with liquid scintillation counting clearly demonstrate the presence of radioactive compounds in the walls of the GI tract at all sacrifice times. In the other tissues and organs examined, radioactivity was only found in trace amounts in the liver. The presence of radioactivity in the GI walls reflected the transit kinetics of drug-enriched contents. The radioactivity in large intestine walls was measurable at otilonium bromide concentrations in the range of micromole equivalents/kg, from 4 to 8 h after drug administration. Total body radioactivity recovery was 95, 101, 24, and 9% at 1.5, 4, 8, and 24 h, respectively. In conclusion, orally administered 14C-otilonium bromide is poorly absorbed systemically, as indicated by the very low plasma radioactivity levels, but it is able to effectively penetrate into the large intestine walls, a recognized target for drugs oriented toward irritable bowel syndrome therapy.

In the muscle layer of the glandular portion of the rat stomach, in vivo capsaicin pretreatment markedly reduced calcitonin gene-related peptide—like immunoreactivity (CGRP-LI) but did not affect substance P—like immunoreactivity (SP-LI). Accordingly, in vitro superfusion of slices of this tissue with capsaicin (10 μmol/L) released CGRP-LI but not SP-LI, whereas both neuropeptides were released by 80 mmol/L K+. Exposure to relatively low-pH (pH 6) physiological salt solution induced an increase in the CGRP-LI outflow that was reduced by 70% in a Ca2+-free medium and was completely abolished by a previous exposure to capsaicin. However, superfusion with pH-6 medium did not produce any detectable SP-LI release. After exposure to pH-6 medium, both capsaicin and high-K+medium were still able to release a consistent quantity of CGRP-LI and SP-LI, respectively. Increased mucosal blood flow induced by acid back-diffusion is considered a protective mechanism against mucosal gastric lesion. The present findings suggest that hydrogen ions diffusing into the gastric wall may promote protective vasodilatation by activating the “efferent” function of capsaicin-sensitive nerves without affecting the secretory process of other intrinsic peptidergic neurons.

The interaction of Otilonium bromide (OB) with binding sites for 63 different receptors and ion channels in appropriate preparations has been investigated. Experiments were also performed in rat colon, the preferred tissue for OB `in vivo' uptake after oral administration.Among the receptors investigated OB binds with subμmaffinity to muscarinic M1, M2, M4, M5and PAF receptors and with μmaffinity to the diltiazem binding site on L type Ca2+channels. In the rat colon OB shows competitive interaction with the verapamil binding site on L type Ca2+channels and with muscarinic M2receptors with IC50of 1020 and 1220 nm, respectively. These findings provide a molecular rationale to explain the spasmolytic action exerted by OB on intestinal smooth muscle. In particular, a combination of antimuscarinic and Ca2+channel blocker properties seems to best account for the action of this compound.

1. The time course and regional distribution of ‘spontaneous’ cutaneous lesions in rats desensitized to capsaicin as newborns was correlated to behavioural observations and regional distribution of substance P-like immunoreactivity (SP-LI) and tachykinin-like immunoreactivity (TK-LI) in various skin areas. 2. ‘Spontaneous’ skin lesions in the form of wounds, scabs and areas of alopecia were observed in 80–90% of rats desensitized to capsaicin. No major sex-related differences were observed with regard to incidence and distribution of the lesions with the possible exception of a lesser tendency to bilateral lesions in female rats. 3. ‘Spontaneous’ skin lesions were almost restricted to the head: the areas most frequently affected were snouts, periocular and retroauricular regions and ventral area of the neck. 4. No major differences were observed between capsaicin- or vehicle-treated animals in spontaneous or novelty-induced grooming as well as in open-field gross behaviour. Likewise, no differences were observed in the mouse-killing behaviour. 5. Both SP-LI and TK-LI in various skin areas were significantly reduced by systemic capsaicin pretreatment. The rank order of various skin areas for SP-LI or TK-LI levels was: snouts > thigh > neck > abdomen ? retroauricular region. 6. Intradermal injection of Arg-neurokinin B, a potent and water soluble derivative of neurokinin B, produced a similar plasma extravasation (Evans blue leakage technique) in the skin of vehicle- or capsaicin-pretreated rats. 7. In capsaicin-desensitized rats fur regrowth (measured at abdominal level, 28 days after shaving) was significantly less than in vehicle-treated animals. 8. The s. c. injection of 1 N HCl in the dorsal thoracic region (an area devoid of ‘spontaneous’ lesions in capsaicin-desensitized animals) produced cutaneous ulcers whose area and depth were greater in capsaicin- than vehicle-treated rats. 9. These findings are consistent with the hypothesis that capsaicin-sensitive nerves play a trophic role in the rat skin and contribute to its ability to react and repair injuries. The most consistent explanation for the restricted localization of ‘spontaneous’ skin lesions to the head seems to be that ‘normal’ injurious factors (such as grooming) operate on a distrophic skin to induce lesions by repeated microtrauma.

This study investigated the role of endogenous and exogenous calcitonin gene-related peptide (CGRP) in water immersion stress (WIS)-induced gastric ulcers in rats.

The incidence and degree of cysteamine- or dulcerozine-induced duodenal ulcers are increased by systemic capsaicin desensitization (50 mg kg−1s.c. 4 days before) in adult rats. Acute administration of capsaicin, but not neurokinins or CGRP, produced a small but distinct plasma extravasation (Evans blue leakage) in the rat proximal duodenum which was absent in capsaicin-pretreated rats. These findings indicate the existence of a capsaicin-sensitive ‘duodenal defence mechanism’ in rats.

Capsaicin Desensitization Increases Degree And Incidence Of Indomethacin-Induced Intestinal Ulcers In Rats, Suggesting The Existence Of A Capsaicin-Sensitive Mechanism(S) In The Protection Of The Intestinal Mucosa Against Indomethacin-Induced Ulceration. Sensory Innervation Thus May Be Involved In The Pathogenesis Of Ulcers Of The Small Bowel, As Well As In Gastric Ulcers. Administration Of Exogenous Cgrp And Somatostatin, Sensory Neuropeptides Which Are Depleted By Capsaicin Desensitization, Does Not Afford Protection Toward The Capsaicin-Induced Aggravation Of Intestinal Ulcers. The Protective Effect Of Exogenous Prostaglandins Toward Indomethacin-Induced Intestinal Ulceration Is Not Mediated By Capsaicin-Sensitive Nerve Fibers.

Systemic capsaicin pretreatment worsens trinitrobenzene sulphonic acid-induced colitis but has no effect on colitis induced by ethanol or acetic acid. The influence of capsaicin-sensitive fibres on experimentally-induced colitis seems to depend upon the type of ulcerogenic stimuli in relation to its chronic nature.

Capsaicin desensitization increases the degree of indome-thacin-induced gastric ulcers in sham-operated but not in adrenal-ectomized rats. These results suggest that adrenals play a role in the capsaicin-sensitive “gastric defence mechanism”.

Subcutaneous administration of cholecystokinin-8 (CCK-8, 10–100 μg/kg) reduces in a dose-dependent manner gastric lesions induced by 96% ethanol in rats, and CCK-4, CCK-7, and the CCK-8 nonsulfated form (all up to 100 μg/kg sc) were inactive. The presence of the entire molecule and sulfation of the tyrosine in position 2 are necessary for the mucosal protective properties of CCK-8 against 96% ethanol-induced gastric lesions. These effects are probably at least in part, due to a sulfhydryl-sensitive process.