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Interdepartmental graduate studies in clinical pharmacology: a practical model.

The discipline of Clinical Pharmacology serves many purposes and plays a critical role in therapeutic education, especially in a medical school. An effective program bridges the gap between basic pharmacology and clinical practice. A clinical pharmacology program must provide the student with the necessary information to employ the basic pharmacology knowledge gained in formatting a successful therapeutic plan. The program is built around the student and brings together the best to be offered in 2 or more disciplines; it requires diverse disciplines to work together in a variety of departments and centers which cut across disciplinary lines. In order to facilitate this interaction, the Division of Clinical Pharmacology at the University of Miami embarked on establishing a Ph.D. program with an emphasis on Clinical Pharmacology utilizing an already established unique program referred to as "Interdepartmental Graduate Studies". To enter the structured Ph.D. program the students must be among the fellowship awardees of the Interdepartment Graduate Studies Program, which is administered by social committees with specific roles, directions and guidelines. The students follow the general requirements of the Ph.D. degree set forth by the graduate school. Students attend formal classes tailored to their program of interest based on the committee's recommendations in the respective departments involved. The significance of this program is that it can be tailored to fit individual areas of interest leading to a well-developed researcher who is neither overspecialized nor undereducated and able to make rational decisions in an age of multiple therapies.

Academic Dissertations as Topic↗

A survey of predoctoral dental basic pharmacology education.

A survey of fifty-one of the fifty-three dental schools in the continental United States provided information about pharmacology curriculum content and time allocation. Most dental schools offer a traditional didactic course in basic pharmacology, with about 50 percent of the medical school-based (MSB) and 75 percent of the dental school-based (DSB) programs providing additional pharmacology material in other basic and clinical courses. The four combined medical-dental (M-D) student courses have more hours of instruction, clinical conferences and reviews, and number of instructors than either the dental school- or medical school-based courses. DSB and MSB pharmacology courses were similar in most regards, with a relatively low compliance with the current curriculum guidelines. The DSB and MSB courses provided more time for neuropharmacology and less time for agents related to various organ systems than the M-D courses. There is considerable potential to improve pharmacology instruction by expanding the inclusion of pharmacology in other courses, increasing the number of clinical conferences and discussions, and offering problem-based-learning sessions.

Curriculum↗

[Activity of the pharmacology department of the I.M. Sechenov Moscow medical academy over the last 40 years (on the 70th birthday of academician of the Russian academy of medical sciences Dmitriĭ Aleksandrovich Kharkevich].

The Department of Pharmacology of the Moscow Medical Academy has a renowned history of long standing. The course of pharmacology was read for the first time at the Medical Faculty of the Moscow University in 1764. The Department of Pharmacology was organized in 1804 and was headed during its existence by many eminent scientists (see the Table) who richly contributed to the development of Russian Pharmacology. The history of the Department of Pharmacology of the Moscow Medical Academy from the time of its foundation till 1957 has been set forth briefly by collaborators of the Department in a series of publications (V. G. Dagurov and A. A. Myazdrikova, 1981;. V. G. Dagurov, 1983, 1987; D. N. Samoilov, 1991). This article is dedicated to 70th birthday of professor D. A. Kharkevich and 40 years (1957-1997) of this activity in the department of pharmacology of the Sechenov Moscow Medical Academy. In 1957 D. A. Kharkevich was appointed as a docent, in 1963--professor and since 1964--he was been the chairman of this department.

History, 20th Century↗

Fluid and pharmacological agents for adhesion prevention after gynaecological surgery.

BACKGROUND: Pelvic surgery is associated with high rates of both de novo adhesion formation and adhesion reformation. Since subsequent fertility is reduced with increasing severity of periadnexal adhesions, pelvic adhesions will remain a clinical problem in infertility patients. Steroids, antihistamines and heparin were amongst the first substances to be advocated for adhesion prevention. More recently icodextrin 4%, hyaluronic acid agents and SprayGel have been used. This review aims to evaluate the role of fluid and pharmacological agents in the prevention of adhesions in fertility-conserving gynaecological surgery. OBJECTIVES: To investigate fluid and pharmacological agents for adhesion prevention when used as adjuvants during pelvic surgery. SEARCH STRATEGY: This review has drawn on the search strategy developed for the Menstrual Disorders and Subfertility Group. The following databases were searched: the Cochrane Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. SELECTION CRITERIA: Randomised controlled trials investigating the use of fluid and pharmacological agents to prevent adhesion formation after fertility-conserving gynaecological surgery. DATA COLLECTION AND ANALYSIS: Data extraction and analysis was performed independently by two authors (Metwally M and Watson A). Two-by-two tables were generated for dichotomous outcomes and expressed as odds ratios (OR) with 95% confidence intervals (CI). For continuous outcomes a standardised mean difference was used. MAIN RESULTS: There is no evidence of benefit from the use of steroids, dextran or other pharmacological agents in any of the outcomes. The use of hyaluronic acid agents may decrease adhesion formation (OR 0.31, 95% CI 0.19 to 0.51) and prevent the deterioration of pre-existing adhesions (OR 0.28 (95% CI 0.12 to 0.66). There is insufficient evidence for the use of icodextrin 4% or SprayGel as adhesion-preventing agents. None of the studied agents has been shown to improve the pregnancy rate when used as an adjunct during pelvic surgery. AUTHORS' CONCLUSIONS: The current evidence for the use of fluid and pharmacological agents for the prevention of adhesions is limited. There is no evidence on any benefit for improving pregnancy outcomes when pharmacological and fluid agents are used as an adjunct during pelvic surgery. There is insufficient evidence for the use of the following agents: steroids, icodextrin 4%, SprayGel and dextran in improving adhesions following surgery. There is some evidence that hyaluronic acid agents may decrease the proportion of adhesions and prevent the deterioration of pre existing adhesions. However, due to the limited number of studies available, this evidence should be interpreted with caution and further studies are needed.

Anticoagulants↗

Clinical pharmacology of antiepileptic drug use: "clinical pearls about the perils of patty".

This Clinical Pharmacology Problem Solving (CPPS) Unit is for use with fourth- or fifth-year pharmacy students and third- or fourth-year medical students during conferences held when they are taking either a rotation in Neurology or Clinical Pharmacology. It may also be used for house staff teaching of residents in Neurology, Pediatrics, Internal Medicine, and Family Practice and fellows in Clinical Pharmacology. This material was prepared for a Teaching Clinic in Clinical Pharmacology taught by Claire M. Lathers, PhD, FCP, Hugh J. Burford, PhD, FCP, and Cedric M. Smith, MD, FCP, and sponsored by the American College of Clinical Pharmacology, September 19-20, 1992, Washington, DC. This workbook includes: (1) an introduction to the Clinical Pharmacology Problem Solving (CPPS) Unit; (2) the learning objectives of the clinical simulation; (3) a pretest; (4) four clinical episodes occurring over many years in the life of a patient; (5) answers to the pretest; (6) a posttest; (7) answers to the posttest.

Adult↗

The diversity of subunit composition in nAChRs: evolutionary origins, physiologic and pharmacologic consequences.

Nicotinic acetylcholine receptors are made up of homologous subunits, which are encoded by a large multigene family. The wide number of receptor oligomers generated display variable pharmacological properties. One of the main questions underlying research in molecular pharmacology resides in the actual role of this diversity. It is generally assumed that the observed differences between the pharmacology of homologous receptors, for instance, the EC(50) for the endogenous agonist, or the kinetics of desensitization, bear some kind of physiologic relevance in vivo. Here we develop the quite challenging point of view that, at least within a given subfamily of nicotinic receptor subunits, the pharmacologic variability observed in vitro would not be directly relevant to the function of receptor proteins in vivo. In vivo responses are not expected to be sensitive to mild differences in affinities, and several examples of functional replacement of one subunit by another have been unravelled by knockout animals. The diversity of subunits might have been conserved through evolution primarily to account for the topologic diversity of subunit distribution patterns, at the cellular and subcellular levels. A quantitative variation of pharmacological properties would be tolerated within a physiologic envelope, as a consequence of a near-neutral genetic drift. Such a "gratuitous" pharmacologic diversity is nevertheless of practical interest for the design of drugs, which would specifically tackle particular receptor oligomers with a defined subunit composition among the multiple nicotinic receptors present in the organism.

Acetylcholine↗

Use of non-pharmacological therapies among patients with osteoarthritis.

BACKGROUND AND AIMS: Non-pharmacological therapies are an important component of treatment for osteoarthritis (OA), but they may be under-used. This study examined the prevalence of self-reported use of common non-pharmacological therapies, as well as patient and physician-related predictors of use. METHODS: Subjects included 205 veterans who completed a survey regarding OA symptoms and treatments. Analyses examined the prevalence of use of three specific non-pharmacological therapies: exercise, physical therapy (PT), and dietary/herbal supplements. We also examined whether patient variables (demographics, clinical characteristics, and perceived helpfulness of non-pharmacological therapies) and physician characteristics (age, gender, race, and recommendation of non-pharmacological therapies) were associated with use of each therapy. RESULTS: Forty-six percent of subjects reported current use of exercise, 11% reported using PT, and 12%, dietary/herbal supplements. Patient demographic and clinical characteristics were generally poor predictors of use of non-pharmacological therapy. However, females were more likely to report exercising than males (p<0.05), and patients with greater disease severity were more likely to report current use of PT (p<0.001). Patients' perceived helpfulness of each therapy significantly predicted use (p<0.05). Physician demographic characteristics were not strong predictors of patients' use of therapy, but physician recommendation for exercise and PT predicted patients' use (p<0.05). CONCLUSIONS: Among this sample of veterans with OA, there was relatively low use of exercise, PT, and dietary/herbal supplements. Patients' perceptions of treatment helpfulness and physician recommendations strongly predicted use. These results signal the importance of interventions aimed at educating both patients and physicians about these therapies.

Aged↗

Occurrence, pharmacology and function of presynaptic alpha2-autoreceptors in alpha2A/D-adrenoceptor-deficient mice.

The occurrence, pharmacological properties and function of alpha2-autoreceptors were studied in hippocampal slices, occipito-parietal cortex slices, segments of heart atria and segments of the vas deferens of wildtype (WT) mice and mice in which the alpha2 A/D-adrenoceptor gene had been disrupted (alpha2 A/D(KO)). Tissues were preincubated with [3H]-noradrenaline and then superfused and stimulated electrically. Stimulation periods for brain slices consisted either of 1 pulse or of 2-64 pulses delivered at 1-s intervals; stimulation periods for peripheral tissues consisted either of 1 POP (pseudo-one-pulse; brief burst of 20 pulses/50 Hz) or of 2-4 POPs delivered at 1-s intervals. Single pulses or POPs were used to study the effect of medetomidine and its interaction with antagonists. One or more pulses or POPs per stimulation period were used to study alpha2-autoinhibition. Medetomidine decreased the evoked overflow of tritium in WT tissues. In alpha2 A/D(KO) tissues, the inhibition was slightly (peripheral tissues) or greatly (brain slices) attenuated but not abolished. Phentolamine, rauwolscine, spiroxatrine, 2-(2,6-dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane (WB 4101), tolazoline and prazosin antagonized the effect of medetomidine in all tissues. Their pKd values against medetomidine were compared with pKd values at prototypical alpha2 binding sites by means of a correlation analysis. For WT brain and atrial autoreceptors, the correlations indicated an alpha2D pharmacology, whereas for WT vas deferens autoreceptors they favoured an alpha2B pharmacology. In the KO tissues, any correlation with alpha2D was lost, and the non-alpha2 A/D-autoreceptors displayed alpha2B or alpha2C pharmacology. When 2 or more pulses or POPs were applied to WT tissues per stimulation period, the pulse number-overflow curve (POP number-overflow curve) was flat, indicating that overflow elicited by p pulses (POPs) was much smaller than p times the overflow elicited by a single pulse (POP); moreover, rauwolscine caused a pulse (POP) number-dependent and, at high pulse (POP) numbers, large increase in evoked tritium overflow. In alpha2 A/D(KO) tissues, the pulse (POP) number-overflow curve was much steeper, indicating that overflow elicited by p pulses (POPs) was closer to p times the overflow elicited by a single pulse (POP); moreover, rauwolscine caused no (atria) or only a small increase in overflow, and did so in brain slices only at high pulse numbers (16 and 64). In conclusion, the predominant alpha2D pharmacology of the autoreceptors in WT tissues supports the idea that the main mammalian presynaptic alpha2-autoreceptors belong to the alpha2 A/D subtype. However, alpha2 A/D-deficient animals also possess autoreceptors. As expected, these non-alpha2 A/D-autoreceptors display alpha2B or alpha2C pharmacology. In WT animals, alpha2B- or alpha2C-autoreceptors or both may coexist with alpha2 A/D-autoreceptors, at least in peripheral tissues. Little autoinhibition by released noradrenaline in trains of pulses remains when the alpha2 A/D-adrenoceptor is lacking, again in accord with a predominance of alpha2 A/D-autoreceptors.

Adrenergic alpha-Agonists↗

PET-measured heterogeneity in longitudinal myocardial blood flow in response to sympathetic and pharmacologic stress as a non-invasive probe of epicardial vasomotor dysfunction.

PURPOSE: We investigated whether a myocardial perfusion gradient during pharmacologically induced hyperemia also occurred during sympathetic stimulation with cold pressor testing (CPT), which commonly induces a paradoxical coronary vasoconstriction in individuals with coronary risk factors. METHODS: Myocardial blood flow (MBF) was measured in absolute units (ml/g/min) with 13N-ammonia and PET at rest, during CPT, and during pharmacologic vasodilation in 59 participants with coronary risk factors ("at risk") and in 43 healthy individuals (controls). MBF was assessed globally as mean MBF, and in the mid and mid-distal myocardium of the left ventricle (LV). A decrease in MBF from mid to mid-distal LV myocardium was defined as MBF difference indicative of a perfusion gradient. RESULTS: The change in mean MBF to CPT (DeltaMBF) in the at-risk group was significantly reduced compared with controls (0.05+/-0.19 vs 0.31+/-0.20 ml/g/min, p<0.0001), whereas mean MBF during pharmacologic vasodilation in the at-risk group tended to be lower than in controls (1.72+/-0.71 vs 2.00+/-0.64 ml/g/min, p=NS). Absolute MBFs during CPT and pharmacologic vasodilation were significantly lower in the mid-distal than in the mid LV myocardium, resulting in a significant MBF difference in the at-risk group (0.15+/-0.06 and 0.27+/-0.12 ml/g/min, p<0.0001) that was not observed in controls (0.007+/-0.05 and 0.014+/-0.10 ml/g/min, p=NS). In the at-risk group there was a significant correlation between the difference of mid to mid-distal MBF during CPT and that during pharmacologic vasodilation (r=0.43, p<0.004), suggesting functional alterations of epicardial vessels as the predominant cause for the observed MBF difference. CONCLUSION: The relative decrease in MBF from the mid to the mid-distal left-ventricular myocardium suggests an intracoronary pressure decline during CPT and pharmacologic vasodilation, which is likely to reflect an impairment of flow-mediated epicardial vasomotor function.

Adult↗

[Non pharmacological treatment of migraine].

Actual recommendations for treatment of migraine consist both of pharmacological and non-pharmacological treatment. The latter enables the patient higher responsibility and self-efficacy in coping with migraine. Therefore, the active involvement in the treatment of the patients is obligatory in all psychological pain therapy methods. Focus of therapy are emotional, cognitive, behavioural and social factors of migraine illness, with the aim to modify unfavourable habits and migraine attack-inducing factors. As non-pharmacological methods counselling, relaxation training, biofeedback and cognitive-behavioural treatments are employed. The long-term effects are comparable with those of pharmacological treatment, combination of pharmacological and non-pharmacological treatment lead to even higher efficacy and is often indicated. In case of headache in children, behavioural therapy should be the method of first choice. In the text, empirically proven methods of psychological pain therapy in migraine will be explained.

Biofeedback, Psychology↗

Pharmacology in space. Part 2. Controlling motion sickness.

In this second article in the two-part series on pharmacology in space, Claire Lathers and colleagues discuss the pharmacology of drugs used to control motion sickness in space and note that the pharmacology of the 'ideal' agent has yet to be worked out. That motion sickness may impair the pharmacological action of a drug by interfering with its absorption and distribution because of alteration of physiology is a problem unique to pharmacology in space. The authors comment on the problem of designing suitable ground-based studies to evaluate the pharmacological effect of drugs to be used in space and discuss the use of salivary samples collected during space flight to allow pharmacokinetic evaluations necessary for non-invasive clinical drug monitoring.

Humans↗

Non-pharmacological pain-relieving therapies in individuals with spinal cord injury: a patient perspective.

OBJECTIVE: To assess the non-pharmacological treatments used and preferred by patients with spinal cord injury and pain. DESIGN: A cross-sectional descriptive study. INTERVENTIONS: One hundred and twenty three patients with spinal cord injury, matched for gender, age, level of lesion and completeness of injury were assessed in 1999 at the Spinalis SCI unit, Stockholm, Sweden and followed-up in a mailed survey 3 years later. In total, 82.1% of the questionnaires (n=101) were returned. Ninety of these patients still suffered pain and were thus included in the study. MAIN OUTCOME MEASURES: Pain questionnaires, visual analogue scale (VAS), Hospital Anxiety and Depression Scale and Life Satisfaction instrument. RESULTS: 63.3% of the patients had tried non-pharmacological treatments, where acupuncture, massage and transcutaneous electrical nerve stimulation (TENS) were the most commonly tried. Predictive for having tried non-pharmacological treatment were high ratings of pain intensity, presence of aching pain, and cutting/stabbing pain. CONCLUSION: Massage, and heat were the non-pharmacological treatments reported to result in the best pain alleviation. Results from our study suggest that we need to (re)evaluate the treatments offered to patients with spinal cord injury and pain and combine non-pharmacological and pharmacological treatments.

Acupuncture Therapy↗

The efficacy of non-pharmacological interventions in the management of procedural pain in preterm and term neonates. A systematic literature review.

BACKGROUND: Neonates in a neonatal intensive care unit are exposed to a high number of painful procedures. Since repeated and sustained pain can have consequences for the neurological and behaviour-oriented development of the newborn, the greatest attention needs to be paid to systematic pain management in neonatology. Non-pharmacological treatment methods are being increasingly discussed with regard to pain prevention and relief either alone or in combination with pharmacological treatment. AIMS: To identify effective non-pharmacological interventions with regard to procedural pain in neonates. METHODS: A literature search was conducted via the MedLine, CINAHL, Cochrane Library databases and complemented by a handsearch. The literature search covered the period from 1984 to 2004. Data were extracted according to pre-defined criteria by two independent reviewers and methodological quality was assessed. RESULTS: 13 randomised controlled studies and two meta-analyses were taken into consideration with regard to the question of current nursing practice of non-pharmacological pain management methods. The selected interventions were "non-nutritive sucking", "music", "swaddling", "positioning", "olfactory and multisensorial stimulation", "kangaroo care" and "maternal touch". There is evidence that the methods of "non-nutritive sucking", "swaddling" and "facilitated tucking" do have a pain-alleviating effect on neonates. CONCLUSIONS: Some of the non-pharmacological interventions have an evident favourable effect on pulse rate, respiration and oxygen saturation, on the reduction of motor activity, and on the excitation states after invasive measures. However, unambiguous evidence of this still remains to be presented. Further research should emphasise the use of validated pain assessment instruments for the evaluation of the pain-alleviating effect of non-pharmacological interventions.

Humans↗

Pressure distention compared with pharmacologic relaxation in vein grafting upregulates matrix metalloproteinase-2 and -9.

OBJECTIVE: Autogenous vein bypasses are a common and effective method to treat occlusive disease. During surgical preparation, veins are routinely pressure distended to overcome vasospasm and twists. Distention, however, is believed to promote vascular remodeling and contribute to decreased graft patency. Pharmacologic vasorelaxation with a combination of effective vasodilators has been suggested as an alternative to pressure distention. The extracellular matrix (ECM)-degrading matrix metalloproteinases (MMPs) have been implicated in vascular remodeling and neointima formation. The purpose of the present study was to compare the effects of pressure distention with pharmacologic vasorelaxation on graft remodeling and regulation of MMP-2 and MMP-9 in porcine vein grafts. METHODS: Carotid artery bypass utilizing internal jugular veins was performed in eight female white pigs. Jugular veins were randomized to receive pressure distention (300 mm Hg for 2 minutes) or a combination of vasodilators (the alpha-adrenergic antagonist phenoxybenzamine, 10 micromol/L; the Rho-kinase inhibitor HA-1077 [fasudil], 50 micromol/L; and the calcium-channel blocker nicardipine, 1 micromol/L) for 30 minutes and then were grafted into the carotid arteries. Two weeks after surgery, vein graft samples were analyzed for vessel intimal and medial area, lumen diameter, and ECM composition. Molecular analysis using reverse transcription-polymerase chain reaction, Western immunoblotting, gelatin zymography, and reverse zymography were performed to study the expression and activation of MMP-2 and MMP-9, and tissue inhibitors of MMP (TIMP)-1 and TIMP-2. RESULTS: Pressure distention irreversibly overstretched the porcine jugular vein and increased MMP-2 and MMP-9 proteolytic activity by 40% and 77%, respectively. Two weeks of vein grafting in the carotid arterial bed induced vessel wall thickening, ECM modification, and neointima formation, which were more pronounced in the distended grafts (P < .05) and accompanied by an increase in MMP expression and activity. Distended grafts demonstrated higher percentages of active MMP-9 (17.8% +/- 1.0%) and higher activities of latent (35.5% +/- 3.3%) and active MMP-2 (69.6% +/- 8.8%) than the pharmacologically treated grafts. Protein expression of TIMP-1 and TIMP-2 was downregulated after arterial grafting, but the pharmacologically treated grafts expressed significantly more TIMP-1 protein (by 36.8% +/- 4.1%) than the distended ones. The activities of TIMPs were markedly decreased after grafting, contributing to the upregulated MMP activity. CONCLUSIONS: Pressure distention of vein grafts before implantation, compared with pharmacologic vasodilatation, stimulates neointima formation and augments MMP activities. Pharmacologic vasorelaxation may be clinically superior to distention in attenuating graft remodeling and possibly improving graft patency. CLINICAL RELEVANCE: Autogenous vein bypasses are a common and effective method to treat occlusive disease. This study demonstrated that pressure distention, a common preparatory procedure in bypass surgery, upregulates extracellular matrix-degrading matrix metalloproteinases, which predisposes vein grafts to extensive remodeling and contributes to neointima formation and graft occlusion. The topical application of a combination of vasodilators to the vein graft before implantation may be clinically superior to pressure distention in attenuating graft remodeling and may possibly improve graft patency and reduce secondary surgical interventions.

Animals↗

Reboxetine: a pharmacologically potent, selective, and specific norepinephrine reuptake inhibitor.

BACKGROUND: Reboxetine is a potent antidepressant, with efficacy comparable to that of imipramine, desipramine, and fluoxetine, and has improved side-effect profile. The basis of its efficacy and improved tolerability is sought through studies of reboxetine in a number of pharmacological models of depression. METHODS: Pharmacological selectivity for uptake systems was defined by uptake and binding assays for the three monoamine uptake sites. Specificity was determined in 39 different receptor and 6 enzyme assays. In vivo selectivity was defined by measurement of neuronal firing rates in the locus coeruleus, dorsal raphe, and substantia nigra. Reserpine-induced blepharospasm and hypothermia, clonidine-induced hypothermia, defined reboxetine's in vivo pharmacology. Reboxetine's antidepressant potential was evaluated behaviorally by the tail-suspension test, forced swimming, and the DRL72 operant responding test. RESULTS: Reboxetine is a potent, selective, and specific norepinephrine reuptake inhibitor (selective NRI) as determined by both in vitro and in vivo measurements. Unlike desipramine or imipramine, reboxetine has weak affinity (Ki > 1,000 nmol/L)for muscarinic, histaminergic H1, adrenergic alpha1, and dopaminergic D2 receptors. In vivo action of reboxetine is entirely consistent with the pharmacological action of an antidepressant with preferential action at the norepinephrine reuptake site. Reboxetine showed an antidepressant profile in all tests of antidepressant activity used. Significant decreases in immobility were observed in the tail suspension test and behavioral despair test. Increased efficiency in responding was observed in the DRL72 test. CONCLUSIONS: Reboxetine is a potent, selective, and specific noradrenergic reuptake inhibitor. It has a superior pharmacological selectivity to existing tricyclic antidepressants and selective serotonin reuptake inhibitors when tested in a large number of in vitro and in vivo systems. Given the pharmacological profile, reboxetine is expected to be a selective and potent tool for psychopharmacological research. The use of reboxetine in the clinic will also help clarify the role norepinephrine plays in depression.

Adrenergic Uptake Inhibitors↗

The effect of N-methylation on fenfluramine's neurotoxic and pharmacologic actions.

N-Methylation separates methamphetamine's neurotoxic and pharmacologic effects. In particular, N-methylation eliminates methamphetamine's neurotoxic activity while preserving its behavioral pharmacologic activity. The purpose of the present studies was to determine whether N-methylation could also be used to separate fenfluramine's neurotoxic and pharmacologic effects. Fenfluramine-induced serotonin neurotoxicity was assessed by measuring serotonin axonal markers 2 weeks after fenfluramine administration. Pharmacologic effects of fenfluramine were assessed by measuring fenfluramine-induced anorexia and fenfluramine discrimination. Both fenfluramine and its N-methylated analog, N-methylfenfluramine, produced dose-related effects in food intake, drug-discrimination and neurotoxicity studies. Although N-methylation reduced the neurotoxic potency of fenfluramine, it also reduced its pharmacologic activity. Neurotoxic potency was reduced 4- to 8-fold (depending on brain region), while pharmacologic potency was reduced 4- to 10-fold (depending on paradigm). Notably, N-methylation did not change the efficacy of fenfluramine as a serotonin neurotoxin, anorectic agent or discrimination stimulus. These results indicate that fenfluramine's behavioral and neurotoxic effects, unlike those of methamphetamine, are not dissociated by N-methylation. Further, the present results suggest that the effectiveness of side-chain nitrogen substitution in separating the behavioral and neurotoxic effects of amphetamine derivatives is strongly influenced by ring substitutions.

Animals↗

[Methadone: from pharmacokinetic profile to clinical pharmacology].

In January 2002, the official French methadone legislation prescription was modified. Thus, the number of clinicians authorized to introduce methadone substitution was increased. Knowledge of the pharmacokinetic and pharmacological properties of this compound remains particularly important for its appropriate prescription. Bearing this in mind, we linked methadone pharmacokinetics to its pharmacological use in this article. METHADONE PHARMACOLOGY: Methadone is a synthetic opiate. Its mean bioavailability is around 75%. Cytochrome P450 3A4 and 2D6 are involved in its hepatic metabolism. Its volume of distribution is of around 4 L/kg. The value of half-life elimination is of around 22 hours. These pharmacokinetic properties (long half-life, steady state concentration) are in favour of substitution use of this opiate. In practice, clinicians progressively introduce this substitution therapy to reach 80 mg +/- 20 mg per day, once daily. Therapeutic clinical goals are mainly to reduce craving, withdrawal symptoms, and to manage psychosocial problems and psychiatric co-morbidity. Practitioners should bear the latter in mind once substitution therapy has been appropriately initiated and stabilized. However, wide, interpatient, interindividual variability impacts on pharmacokinetic parameters. Subjects may be either high or poor metabolizers. Thus, bioavibility ranges from 36 to 100%. Induction or inhibition of CYP450 significantly modifies methadone pharmacodynamic properties. Genetic variability and medication can induce non response to substitution, craving, or withdrawal symptoms. PHARMACOLOGICAL INTERACTIONS: We describe here a large number of medications involved in pharmacokinetic or pharmacological interactions. Classical enzymatic inductors, such as antiepileptic molecules (phenobarbital, carbamazepin), antituberculosis compounds (rifampicin), or antiretroviral therapy (efavirenz, nevirapin, ritonavir), could possibly lead to respiratory depression for example. Metabolism inhibitors such as selective serotonin reuptake inhibitors (fluvoxamine, fluoxetine, paroxetine, sertraline) or antifungals of the azol groups could enhance plasma concentration and may sometimes lead to respiratory depression or death. Nevertheless, clinicians should know methadone pharmacokinetic properties and pharmacological interactions for the optimal opiate-dependant patients' management. CLINICAL USE: Clinicians can use plasma concentrations as a useful indicator to reach substitution goals. The methadone plasmatic target value of 400 microg/ml can be recommended for therapeutic drug monitoring. This dosage not only facilitates interaction detection, but also hand encourages communication with the patient.

Cytochrome P-450 Enzyme System↗

Permeation, metabolism and site of action concentration of nicotinic acid derivatives in human skin. Correlation with topical pharmacological effect.

A novel methodology for establishing a pharmacological dose-effect relationship of methyl nicotinate, hexyl nicotinate and nicotinic acid acting as peripheral vasodilators in the skin following topical application is investigated. This methodology involves the estimation of the unbound drug concentration in the aqueous compartment at the site of action in tissue, termed C(*), which was evaluated as the pertinent concentration responsible for the pharmacological effect. Blood capillaries next to the epidermis-dermis boundary were postulated to be the relevant site of action. C(*) was estimated from drug transport parameters for different layers of human cadaver skin determined in vitro. Immunohistochemical studies showed that the plane of separation of skin achieved by heat treatment was between the basal cells of the epidermis and the lamina lucida, confirming the integrity of the epidermis and the dermis used in the experiments. The permeation rate for epidermis increased drastically with increasing lipophilicity of the drug. Dermis permeability was roughly the same for all three compounds. The epidermis represented the major transport barrier in vitro for methyl nicotinate and nicotinic acid but not for hexyl nicotinate. The esters were metabolised to nicotinic acid during tissue permeation to an extent that was rather limited for the epidermis but very pronounced for the dermis. Nonspecific alpha-naphthylacetate-esterase activity was predominantly located in the dermis, which was in agreement with the metabolism results. The drugs were applied each at three different concentrations in vivo to the ventral forearm of healthy human volunteers and vasodilation was evaluated based on skin erythema which was quantified by measuring colour change of reflected light. Area under the curve of the change of colour co-ordinates as a function of time was used as a measure of pharmacological effect. The pharmacological effect of all three drugs was comparable when similar C(*) values were considered, even though the concentrations applied to the skin differed by orders of magnitude. The effect showed a strong positive dependence on C(*). Methyl and hexyl nicotinate showed identical, nearly sigmoidal effect/C(*)-profiles, while the profile for nicotinic acid was linear, suggesting a possible difference in the intrinsic pharmacological potency between the esters and the acid. These results demonstrate the validity of C(*) as the relevant drug concentration for the cutaneous pharmacological effect of the topically applied drugs and underline the usefulness of the presented methodology for establishing dose-response relationships in dermal therapy and expressing bioavailability.

Administration, Topical↗