Manuela Graziani

Khat Chewing from the Pharmacological Point of View: An Update

Khat chewing is deeply rooted in the every day life of people living in the Horn of Africa and in South Arabia, where Catha edulis is endemic. Considered little more than an exotic habit producing just mild pharmacological effects, systematic investigations on its active principles have instead lead to the isolation and chemical characterization of cathinone, a compound structurally related to amphetamine. Three decades of intense experimental and clinical research on khat have depicted a consistently clear picture of its pharmacological and toxicological effects.

Cocaine toxic effect on endothelium-dependent vasorelaxation : An in vitro study on rabbit aorta

Effects of cocaine on vascular endothelium relaxing properties and the related mechanism were investigated in vitro in rabbit aorta. Several vasorelaxing agents with different mechanisms, i.e. acetylcholine, substance P, calcium ionophore A23187, 2,5-di-tert-butylhydroquinone, or sodium nitroprusside, were employed. Cocaine effects on the vascular response to relaxing agents in cumulative (acetylcholine, substance P, or A23187) or single dose (2,5-di-tert-butyl-hydroquinone) were performed in endothelium-intact aortic rings precontracted with phenylephrine. Relaxing activity of cumulative doses of sodium nitroprusside was evaluated in endothelium-denuded aortic rings, in the presence of cocaine. Cocaine significantly reduced endothelium-dependent relaxations induced by acetylcholine, or substance P. By contrast A23187 endothelium-mediated relaxation as well as endothelium-independent relaxation by sodium nitroprusside were unaffected by cocaine. Furthermore, cocaine significantly increased endothelium-dependent relaxation response to 2,5-di-tert-butylhydroquinone, a sarcoplasmic Ca2+-ATPase pump inhibitor, in the aortic rings. These findings indicate that cocaine reduces nitric oxide release from vascular endothelium apparently through the inhibiting action of Ca2+-ATPase pump.

Genders and the concurrent use of cocaine and alcohol: Pharmacological aspects.

AIMS Gender-related differences in the pharmacological effects of addictive drug are an emerging issue. This review examines gender differences in both pharmacokinetic and pharmacodynamic aspects of alcohol and cocaine intake since they cause complex pharmacological interactions, not least the formation of the active metabolite cocaethylene. METHODS The MEDLINE database was searched from 1990 to 2014 in order to find articles related to gender differences in alcohol, cocaine and cocaethylene pharmacokinetics and pharmacodynamics. RESULTS Besides the well known gender differences in alcohol pharmacokinetics, women appear more susceptible to alcohol-mediated brain damage and seem to suffer more than men the acute effects of alcohol on hepatic and gonadal hormones. No significant gender differences have been found in the pharmacokinetics of cocaine taken alone; yet, in women pharmacological sensitivity to the drug seems to vary in relation to menstrual cycle; moreover, progesterone attenuates subjective effects of cocaine in women. Higher ratings at a subjective measure of mental/physical well-being have been observed in women when given cocaine and alcohol, alone or in combination. Finally, among subjects dependent on both alcohol and cocaine, men only benefit from naltrexone, whereas women used more cocaine during the trial and were less compliant to therapy than men. CONCLUSIONS The observed subtle gender differences in the pharmacokinetics and pharmacodynamics of both alcohol and cocaine may have no subtle influence on the natural history of the co-abuse of the two drugs by women.

Testosterone and cocaine: vascular toxicity of their concomitant abuse

Over the last few years, several studies have described an increase in the use of anabolic-androgenic steroids (AAS). More important, frequency of AAS use was significantly associated with frequency of psychotropic drug use, such as cocaine. Since information is not available on the effects of their concomitant abuse, and taking into account that cocaine and testosterone, when singly abused, are known to induce severe adverse effects on vascular system, our purpose was to evaluate in vitro the combined effect of these drugs on platelet and endothelial functions. Results show that testosterone, at concentrations not exerting any appreciably acute effects on their own, is capable of potentiating the cocaine effect on endothelial and platelet functions, indicating that concomitant use of testosterone and cocaine could result in enhancement of the thrombotic risk ascribed to these drugs.

Electrophysiological and metabolic effects of CHF5074 in the hippocampus: Protection against in vitro ischemia

CHF5074 is a non-steroidal anti-inflammatory derivative holding disease-modifying potential for the treatment of Alzheimers disease. The aim of the present study was to characterize the electrophysiological and metabolic profile of CHF5074 in the hippocampus. Electrophysiological recordings show that CHF5074 inhibits in a dose-dependent manner the current-evoked repetitive firing discharge in CA1 pyramidal neurons. This result is paralleled by a dose-dependent reduction of field excitatory post-synaptic potentials with no effect on the paired-pulse ratio. The effects of CHF5074 were not mediated by AMPA or NMDA receptors, since the inward currents induced by local applications of AMPA and NMDA remained constant in the presence of this compound. We also suggest a possible activity of CHF5074 on ASIC1a receptor since ASIC1a-mediated current, evoked by application of a pH 5.5 solution, is reduced by pretreatment with this compound. Moreover, we demonstrate that CHF5074 treatment is able to counteract in hippocampal slices the OGD-induced increase in alanine, lactate and acetate levels. Finally, CHF5074 significantly reduced the apoptosis in hippocampal neurons exposed to OGD, as revealed by cleaved-caspase-3 immunoreactivity and TUNEL staining. Overall, the present work identifies novel mechanisms for CHF5074 in reducing metabolic acidosis, rendering this compound potentially useful also in conditions of brain ischemia.

Opiatergic modulation of preparatory and consummatory components of feeding and drinking

We present data here indicating that stimulation of kappa but not mu opiate receptors influences motivational and consummatory aspects of feeding and drinking. To differentiate mu and kappa mechanisms controlling preparatory (appetitive) and consummatory components of ingestive behavior, the effects of morphine (MORPH), compound U50488H (U50) and naloxone (NAL) were studied in rats trained to negotiate a straight runway using food or water as a reinforcer. At doses that increase feeding and drinking in conditions of free access to food and water (i.e., 1-2 mg/kg IP), MORPH affected neither food- nor water-maintained runway performance. Since 1 mg/kg of NAL is also devoid of effects, mu-opiate mechanisms are probably not involved in food- or water-maintained behavior. Pharmacological manipulation of kappa-opiate mechanisms had complex effects. At 5 mg/kg, NAL accelerated satiation, depressing food intake, without affecting running. U50 did not increase food intake, but accelerated running for food, an effect that was antagonized by a high dose of NAL (5 mg/kg). These findings suggest that motivational and consummatory components of food-maintained runway performance are both activated by kappa-opiate mechanisms. NAL also reduced water intake but had minimal influences on running. In contrast, U50 depressed both water intake and runway performance; rather than being antagonized, these effects were slightly enhanced by NAL. The combined antidipsic and diuretic effects of U50 suggest that kappa-opiate mechanisms play a dissipatory role in water balance. However, the similar antidipsic effects of U50 and NAL, and the fact that NAL did not antagonize the antidipsic effects of U50, suggest that U50 may reduce drinking by mechanisms other than kappa-opiate agonism.

Cardiovascular and Hepatic Toxicity of Cocaine: Potential Beneficial Effects of Modulators of Oxidative Stress

Oxidative stress (OS) is thought to play an important role in the pharmacological and toxic effects of various drugs of abuse. Herein we review the literature on the mechanisms responsible for the cardiovascular and hepatic toxicity of cocaine with special focus on OS-related mechanisms. We also review the preclinical and clinical literature concerning the putative therapeutic effects of OS modulators (such as N-acetylcysteine, superoxide dismutase mimetics, nitroxides and nitrones, NADPH oxidase inhibitors, xanthine oxidase inhibitors, and mitochondriotropic antioxidants) for the treatment of cocaine toxicity. We conclude that available OS modulators do not appear to have clinical efficacy.

Gender differences in pharmacokinetics and pharmacodynamics of methadone substitution therapy

Gender-related differences in the pharmacological effects of drug are an emerging topic. This review examines gender differences in both pharmacokinetic and pharmacodynamic aspects of methadone, a long-acting opioid agonist that is prescribed as a treatment for opioid dependence and the management of chronic pain. Method: We performed a search in the Medline database from 1990 to 2014 in order to find published literature related to gender differences in pharmacokinetics (PK) and pharmacodynamics (PD) of methadone. Results: None of the studies were carried out with the primary or secondary aim to identify any gender differences in the pharmacokinetic profile of methadone. Importantly; high inter-subjects variability in PK parameters was found also intra female population. The reported differences in volume of distribution could be ascribed to the physiological differences between men and women in body weight and composition, taking into account that the dose of methadone was established irrespective of body weight of patients (Peles and Adelson, 2006). On the other hand, the few studies present in literature found no gender difference in some direct pharmacodynamic parameters. Some reports have suggested that female gender is associated with an increased risk for long-QT-related cardiac arrhythmias in methadone maintenance subjects. Conclusion: Even though it may be too simplistic to expect variability only in one parameter to explain inter-individual variation in methadone response, we believe that a better knowledge of gender-related differences might have significant implications for better outcomes in opioid dependence substitution therapy in women.

Non-opioid induction of morphine-6-glucuronide synthesis is elicited by prolonged exposure of rat hepatocytes to heroin.

BACKGROUND Liver metabolism of morphine leads to the formation of morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G), the latter possessing strong opioid activity that however differs from that of the parent compound. In previous studies conducted in rats we have shown that repeated in vivo exposure to phenanthrene class of mu opioid receptor (MOR) agonists or antagonists (heroin, morphine, and naltrexone), but not to non-phenanthrene class of MOR agonist methadone, affects morphine glucuronidation by liver microsomes. METHODS In the present study, we measured the in vitro formation of M3G and M6G by rat hepatocytes incubated for 120 min with morphine (0.1-1.0 mM) after 72h pre-incubation with one of the following MOR agonists: heroin (3.3 or 6.6 microM), morphine (7.8 microM), or methadone (12 microM). The MOR antagonist naltrexone (10 or 25 microM) was also tested, alone or in combination with heroin. The amount of M3G and M6G synthesized was then measured by HPLC method. RESULTS Heroin inhibited M3G synthesis and induced the formation of M6G, which under basal conditions is not synthesized in rats. Heroin effects were not blocked by naltrexone. Morphine, but not methadone, produced effects similar to those of heroin but more modest in intensity. Pre-incubation with naltrexone alone slightly increased M3G synthesis, but had no effect on M6G formation. CONCLUSIONS These results are in agreement with those of previous ex vivo studies and indicate that exposure to heroin or, to a lesser extent, morphine, can affect morphine glucuronidation via direct non-opioid actions on the hepatocytes.

Cardiovascular Mitochondrial Dysfunction Induced by Cocaine: Biomarkers and Possible Beneficial Effects of Modulators of Oxidative Stress.

Cocaine abuse has long been known to cause morbidity and mortality due to its cardiovascular toxic effects. The pathogenesis of the cardiovascular toxicity of cocaine use has been largely reviewed, and the most recent data indicate a fundamental role of oxidative stress in cocaine-induced cardiovascular toxicity, indicating that mitochondrial dysfunction is involved in the mechanisms of oxidative stress. The comprehension of the mechanisms involving mitochondrial dysfunction could help in selecting the most appropriate mitochondria injury biological marker, such as superoxide dismutase-2 activity and glutathionylated hemoglobin. The potential use of modulators of oxidative stress (mitoubiquinone, the short-chain quinone idebenone, and allopurinol) in the treatment of cocaine cardiotoxic effects is also suggested to promote further investigations on these potential mitochondria-targeted antioxidant strategies.