Assessment of anxiolytic and panicolytic effects of dichloromethane fraction from stems of Kielmeyera coriacea.

Kielmeyera coriacea Mart. (Calophyllaceae) is known popularly as "Pau Santo". The hydroethanolic extract (HE) of Kielmeyera coriacea stems and its semi-pure dichloromethane (DCM) constituent produced an antidepressant-like effect in rats. The purpose of this study was to investigate the effects of repeated administration (21 days) by gavage of the DCM fraction (5, 10 or 15mg/kg) in rats submitted to the elevated T-maze (ETM), a model of generalized anxiety and panic disorders. The tricyclic antidepressant imipramine (15mg/kg) was used as a positive control. Rat locomotion was assessed using the open field test (OFT) following each drug treatment. The 2-hydroxy-1-methoxyxanthone (1), aucuparin (2), swertinin (3), 1,3,7-trihydroxy-2-(3-methylbut-2-enyl)-xanthone (4) and 1,3,5-trihydroxy-2-(3-methylbut-2-enyl)-xanthone (5) were identified in DCM fraction, and suggest that the xanthone (4) is related with the antidepressant-like profile of this plant. Pharmacological evaluation showed that DCM fraction (10 and 15 mg/kg) decreased the inhibitory avoidance latency from the closed arm and increased the one-way escape latency from the open arm in the ETM, which is indicative of anxiolytic and panicolytic effects, respectively, as occurs with the positive control, imipramine (15 mg/kg), when compared to their control group (vehicle). Locomotor activity was not significantly altered by the different treatments. This study suggests that the DCM fraction from stems of Kielmeyera coriacea can be an important therapeutic alternative in the treatment of anxiety disorders, such as generalized anxiety and panic disorders.

CNS drug development. Part I: The early period of CNS drugs.

This column begins a new series on central nervous system (CNS) drug development. This series will review developments up to the present day and end with a forward-looking perspective on what to expect over the next 10-20 years. The goal of this series is to explain to practicing clinicians how drugs are developed and why CNS drug development is at an important juncture involving both significant challenges and opportunities. This column (Part 1) reviews the history of CNS drug development from the period before written history through the golden era (i.e., late 1940s-early 1960s) in which the first modern medications for anxiety, bipolar, depressive, and psychotic disorders were discovered by chance. It also describes the early era of rational drug development in which other agents (e.g., thioridazine, fluphenazine, haloperidol, imipramine) were developed based on those first agents. The blueprint laid down for development of antibiotics is reviewed in relation to its impact on CNS drug development. The impact of the blockbuster business model and modern marketing/sales approaches on CNS drug development is also discussed.

Cost effectiveness of pharmacotherapy for the prevention of migraine: a Markov model application.

BACKGROUND: There are few data about the cost effectiveness of prophylactic medications for migraine. Clinical trials have shown several preventive agents to be useful in reducing the frequency of migraine attack while having tolerable side effects. OBJECTIVE: To compare the cost effectiveness of adding preventive treatment to abortive therapy for acute migraine with abortive therapy for acute migraine alone in the primary care setting. METHODS: A Markov decision analytic model with a cycle length of 1 day, a time horizon of 365 days and three health states was used to perform an analysis comparing the cost effectiveness and utility of five treatments for migraine prophylaxis (amitriptyline 75 mg/day, topiramate 100 and 200 mg/day, timolol 20 mg/day, divalproex sodium 1000 mg/day or propranolol 160 mg/day) with treatment of acute migraine alone for the management of migraine in the primary care setting. One-way and probabilistic sensitivity analyses were performed to test the robustness of the results. RESULTS: The expected total annual cost for the use of preventive agents ranged from $US2932 to $US3887, compared with $US3960 for the use of abortive medications only. In the baseline analysis, use of each of the five preventive agents generated more quality-adjusted life-years (QALYs) and incurred lower costs compared with abortive medications only. Monte Carlo Simulation suggested that amitriptyline 75 mg/day was most likely to be considered a cost-effective option versus the other five therapies, followed by timolol 20 mg/day, topiramate 200 mg/day, topiramate 100 mg/day, divalproex sodium 1000 mg/day and propranolol 160 mg/day when the willingness-to-pay (WTP) for society is <$US18 000 per QALY gained. CONCLUSIONS: Preventive medications appear to be a cost-effective approach to the management of migraine in the primary care setting compared with the approach of abortive treatment only. Among those preventive agents, probabilistic sensitivity analysis suggests that, when the societal WTP is <$US18 000 per QALY gained, amitriptyline 75 mg/day is most likely to be considered a cost-effective option.

Biochemical and pharmacological characterization of the serotonin transporter in human peripheral blood lymphocytes.

The serotonin transporter (5-HTT) plays a critical role in the termination of serotonin neurotransmission and represents the prime target for selective serotonin reuptake inhibitors (SSRIs). In the present study, the 5-HTT protein in human peripheral blood lymphocyte was characterized pharmacologically and biochemically. The tricyclic antidepressant drug [(3)H]imipramine, an established ligand for the neuronal and platelet 5-HTT, bound saturably and reversibly to a single population of non-interacting binding sites in fresh human peripheral blood lymphocytes. The affinity of [(3)H]imipramine (K(d)) to the transporter, calculated from association and dissociation kinetic experiments, was similar to that obtained from the equilibrium study. The function of the transporter was studied using high affinity [(3)H]5-HT uptake into fresh lymphocytes. [(3)H]Imipramine binding and [(3)H]5-HT uptake were inhibited by tricyclic antidepressants as well as by SSRIs. Western blot analysis as well as immunoprecipitation analysis revealed labeling of a single protein band of approximately 100 kDa. The presence of the 5-HTT in easily accessible nucleated cells such as peripheral blood lymphocytes might permit molecular genetic studies in mood and anxiety disorder patients, and might enhance the understanding of the different efficacies of antidepressants in depressed patients.

Assessment of differential blockade by amitriptyline and its N-methyl derivative in different species by different routes.

BACKGROUND: Increasing the duration of local anesthesia and/or creating greater differential blockade (i.e., selective block of pain-transmitting nerve fibers) has been attempted by modifying currently available agents. Most drugs show a different profile depending on the model or species studied. This study was designed to investigate the differential nerve-blocking properties of amitriptyline and its quaternary ammonium derivative in rats and sheep. METHODS: The Na+ channel-blocking properties of N-methyl amitriptyline were determined with the patch clamp technique in cultured GH(3) cells. Various functions (motor, nociception, proprioception-ataxia) were compared in rats (spinal and sciatic nerve blockade) and sheep (spinal blockade) with amitriptyline, N-methyl amitriptyline, lidocaine, and bupivacaine (partially from historical data). RESULTS: In vitro testing revealed N-methyl amitriptyline to be a potent Na+ channel blocker similar to amitriptyline but with a much longer duration of action. All drug concentrations tested in both the sciatic nerve model and the spinal block model produced no significant differential blockade in rats. Three of six rats in the 20-mM N-methyl amitriptyline group showed residual blockade 4 days after sciatic nerve injection. However, in the sheep spinal model, amitriptyline and in particular N-methyl amitriptyline displayed significant differential blockade at most time points. Sheep data for lidocaine and bupivacaine seemed to be more comparable to the clinical experience in humans than did rat data. CONCLUSIONS: Amitriptyline and N-methyl amitriptyline are potent Na+ channel blockers and show greater differential blockade in sheep than in rats. This differential blockade in sheep is greater than that produced by lidocaine or bupivacaine.

Mirtazepine: heir apparent to amitriptyline?

"What's new in therapeutics?" will examine and evaluate drugs that may have a place in hospice, palliative, and long-term care. Mirtazepine will be examined and evaluated. Mirtazepine is a potential alternative anti-depressant with multiple additional benefits. It is an atypical anti-depressant, which has both noradrenergic and specific serotonergic receptor antagonism (NaSSa), and a unique pharmacological profile. Mirtazepine appears to be a "designer drug" for palliative medicine with a number of benefits, but cost may be a drawback.

Dimensional assessment of onset of action of antidepressants: a comparative study of moclobemide vs. clomipramine in depressed patients with blunted affect and psychomotor retardation.

The onset of action (during the first 2 weeks of treatment) of moclobemide (450 mg/day), a reversible MAO-A inhibitor, was compared in a double-blind, multi-center trial with clomipramine (150 mg/day) on dimensional and global depressive symptoms in 124 hospitalized patients suffering from a major depressive episode according to DSM-III-R criteria and with blunted affect and retardation. An earlier efficacy was found for moclobemide with significant treatment differences in favor of moclobemide, which were detected on negative symptoms (anhedonia, blunted affect and retardation) on days 7 and 10. The overall effect on depression at the end of the 4-week trial period was similar in both groups. However, a higher termination rate due to lack of efficacy was found with moclobemide (10 vs. 3). The tolerability was significantly better for moclobemide, as shown by the lower frequency of adverse events.

A risk-benefit assessment of mirtazapine in the treatment of depression.

Mirtazapine is the first of a new class of antidepressants, the noradrenergic and specific serotonergic antidepressants (NaSSA). Its antidepressant effect appears to be related to its dual enhancement of central noradrenergic and serotonin 5-HT1 receptor-mediated serotonergic neurotransmission. Mirtazapine possesses a number of useful pharmacokinetic characteristics such as good absorption, linear pharmacokinetics over the recommended dosage range (15 to 80 mg/day), and an elimination half-life of 20 to 40 hours, thereby allowing once-daily administration. However, since the drug is extensively metabolised by the hepatic cytochrome P450 (CYP) system and is excreted mainly in the urine, its clearance may be reduced by hepatic or renal impairment. In vitro data suggest that from a clinical point of view it is unlikely that mirtazapine would inhibit the metabolism of coadministered drugs metabolised by CYP1A2, CYP2D6 or CYP3A4. In vivo data from a study in extensive and poor metabolisers of debrisoquine indicate that strong inhibitors of CYP2D6 would have no effect on the concentration of racemic mirtazapine. In some placebo-controlled studies mirtazapine showed an early onset of antidepressant action, with significant reductions in total Hamilton Depression Rating Scale and Montgomery-Asberg Depression Rating Scale scores (relative to placebo) noted as early as 1 week after starting treatment. This therapeutic advantage was subsequently maintained during treatment, with mirtazapine proving significantly superior to placebo at treatment end-point in the majority of studies. In comparative trials, the antidepressant efficacy of mirtazapine was comparable with that of tricyclic antidepressants such as amitriptyline, clomipramine and doxepin, and in 2 studies superior to that of trazodone and fluoxetine. Mirtazapine appears to have a broad spectrum of activity, reflected in its efficacy in a variety of clinical settings. Its additional beneficial effects on the symptoms of anxiety and sleep disturbance associated with depression may reduce the need for concomitant anxiolytic and hypnotic medication seen with some antidepressants. Mirtazapine has demonstrated superior tolerability to the tricyclic antidepressants and trazodone, primarily on account of its relative absence of anticholinergic, adrenergic and serotonin-related adverse effects, in particular gastrointestinal adverse effects and sexual dysfunction. It appears that increased sedation associated with the drug is related to subtherapeutic dosages, and that it is reported in substantially fewer patients when the drug is used in appropriate dosages (> or = 15 mg as a single evening dose) from the beginning of treatment. Although 2 cases of reversible severe symptomatic neutropenia have been reported in clinical trials, there have been no additional reports of symptomatic neutropenia since the introduction of this drug to various countries in September 1994. Currently available data and initial clinical experience suggest that with its combination of dual action, simple pharmacokinetics, and clinical efficacy and tolerability, mirtazapine appears to be an important advance in the pharmacotherapy of depression.

A physiologic assessment of intrathecal amitriptyline in sheep.

BACKGROUND: Intrathecal injection of amitriptyline enhances antinociception from intravenous morphine and reduces neuropathic pain behavior in animals. This study represents part of a preclinical assessment of intrathecal amitriptyline to determine its safety for use in humans. METHODS: Low thoracic intrathecal, femoral, and pulmonary arterial catheters were inserted in 18 adult ewes, followed 96 h later by intrathecal injection of saline or 5 mg amitriptyline and by determination of spinal cord blood flow, hemodynamic variables, behavioral changes, cerebrospinal fluid concentrations of catecholamines and amitriptyline, and spinal tissue concentrations of amitriptyline. In six other ewes, low thoracic intrathecal and femoral arterial catheters were inserted and blood pressure and heart rate were measured after intrathecal injection of saline or 0.25, 1, or 5 mg amitriptyline. Four other ewes received cervical intrathecal injection of 5 and 10 mg amitriptyline, and antinociception was determined. RESULTS: Thoracic intrathecal injection of amitriptyline produced dose-dependent sedation but did not significantly affect spinal cord blood flow or hemodynamic variables. Spinal cord tissue concentrations of amitriptyline were 100 times greater in tissue near the tip of the thoracic intrathecal catheter compared with cervical cord tissue. Cerebrospinal fluid concentrations of catecholamines did not significantly change after amitriptyline was administered. Cervical intrathecal injection of 5 mg amitriptyline produced mild antinociception, whereas 10 mg produced intense sedation and, in one sheep, seizures and death. CONCLUSIONS: Although other preclinical toxicity studies are necessary before introducing intrathecal amitriptyline for use in humans, this study did not reveal dangerous changes in blood pressure or spinal cord blood flow from this agent.

Rational drug use in the treatment of depression.

New drugs are being developed for the management of depression in response to the growing awareness of the prevalence and disability associated with the disorder and the need for agents with improved side effect profiles. All antidepressants are equally effective for treating uncomplicated unipolar depression without psychotic features. For patients with atypical depression with prominent anxiety, agitation, sleep loss, and irritability, monoamine oxidase inhibitors are the first choice. Data are accumulating supporting the efficacy of selective serotonin reuptake inhibitors (SSRIs) in these depressive subtypes. Factors to consider when choosing an antidepressant include spectrum of adverse effects, long-term tolerability, dosing schedule, clinically significant drug interactions, underlying medical conditions, earlier response to therapy, and pharmacoeconomics. Based on these criteria, it is suggested that a trial with the SSRIs be attempted first. Venlafaxine and nefazodone are newer agents with mechanisms of action that have advantages over tricyclic antidepressants and monoamine oxidase inhibitors. Choosing a drug that is effective, tolerable, and convenient will improve the likelihood of achieving and maintaining a full remission. It will also decrease the morbidity and mortality of this very treatable disease.

Fluvoxamine and tricyclic antidepressants (TCAs): how do the TCAs compare as "new" drugs with established fluvoxamine?

The tricyclic antidepressants (TCAs) are still considered as first-line treatment for depression, despite the availability of the selective serotonin reuptake inhibitors (SSRIs). This paper considers the current situation in reverse by assuming that only the SSRIs, in particular fluvoxamine, are available and the TCAs (amitriptyline, imipramine, clomipramine and dothiepin) are the potential "new" drugs. The criteria for an "ideal" antidepressant are discussed and the efficacy, safety and cost-effectiveness of these agents are compared.

Electrophysiological assessment of the effects of antidepressant treatments on the efficacy of 5-HT neurotransmission.

The efficacy of serotoninergic (5-HT) neurotransmission was assessed in the rat brain following different types of antidepressant treatments. First, the firing rate of 5-HT neurons was assessed. Second, the responsiveness of postsynaptic neurons to 5-HT was evaluated by applying directly onto these neurons the neurotransmitter by microiontophoresis. Finally, the effect of the electrical stimulation of the 5-HT pathway on the firing activity of the same postsynaptic neurons was studied in order to determine the efficacy of synaptic transmission. Long-term administration of tricyclic antidepressant drugs induces a sensitization of rat forebrain neurons to 5-HT without altering 5-HT neuron properties. This sensitization results in an enhancement of the effect of the stimulation of the 5-HT pathway on the firing activity of postsynaptic neurons. Long-term administration of antidepressant monoamine oxidase inhibitors also results in an enhancement of the effectiveness of the stimulation of the 5-HT pathway. This is not due to a modification of postsynaptic neuron properties, since there is no enhancement of their responsiveness to 5-HT. Furthermore, the function of the terminal 5-HT autoreceptor is not altered by long-term treatment with a monoamine oxidase inhibitor. Therefore, the enhancement of 5-HT neurotransmission produced by this type of drugs is due to an increased availability of releasable 5-HT. The acute administration of 5-HT reuptake blockers does not enhance the efficacy of the stimulation of the 5-HT pathway. However, their long-term administration produces such an enhancement without altering the responsiveness of postsynaptic neurons to 5-HT. This modification of 5-HT transmission is attributable to a desensitization of the terminal 5-HT autoreceptor, thereby allowing a greater amount of 5-HT to be released per impulse in the synaptic cleft. The electrophysiological assessment of the effects of these different types of antidepressant treatments on the 5-HT system therefore revealed as a common effect an enhancement of 5-HT neurotransmission, albeit each one achieving this via a different mechanism.

[Treatment with tianeptine of depressive disorders in drug addicts under withdrawal. Assessment of efficacy and study of dependence]. / Traitement par la tianeptine des syndromes dépressifs des toxicomanes sevrés. Appréciation de l'efficacité et recherche de dépendance.

The study concerns the use of a new antidepressant, tianeptine, as a treatment of depressive and/or amotival syndrome, in 30 drug addicts, detoxified from opiates. From a thymoanaleptic point of view, 85% of the patients exhibit a positive result after 28 days of treatment with 37.5 mg/day. These good results are confirmed by the evolution of the Hamilton Depression Rating Scale global score, which significantly decreases from D0 to D14 and from D14 to D28. The acceptability of the antidepressant is good. Anticholinergic side-effects are very uncommon. Tianeptine appears devoid of any obvious psychostimulant or sedative effect. The drug compliance, estimated by counting the tablets, is very satisfying: there is no tendency to a spontaneous increase of dosing. The follow-up of the patients after drug cessation has not shown any symptoms suggesting psychological or physical dependence towards the drug. During this study in subjects particularly predisposed to the abuse of psychoactive drugs, tianeptine has not induced anything suggesting the possibility of drug abuse or tolerance.

Critical assessment of noradrenaline uptake in synaptosomal preparations.

Synaptosomes and other subcellular organelles were prepared from rat brain using a vertical rotor. The preparation time was reduced by up to 60% compared to conventional techniques. Uptake of [3H]-(-)-noradrenaline into subcellular fractions was characterized. The characteristics of this uptake were dependent on the subcellular composition and anatomical origin. Various methods of correction for energy independent processes were compared, but only sodium ion removal from the medium selectively inhibited the energy dependent uptake mechanism. Kinetic analysis of data revealed that high and low affinity uptake systems were dependent on the fraction under analysis. Noradrenaline uptake was not exclusively localised in noradrenergic terminals. Selective inhibitors of the noradrenaline uptake process (tricyclic antidepressants) inhibited energy dependent uptake completely only in purified synaptosomes prepared from cortex. In whole brain synaptosomal fractions, noradrenaline was partially accumulated into dopaminergic neurones; this uptake process was not inhibited by tricyclic antidepressants.

Tricyclic antidepressants vary in decreasing alpha 2-adrenoceptor sensitivity with chronic treatment: assessment with clonidine inhibition of acoustic startle.

1 Clonidine inhibition of the acoustic startle reflex in the rat was used as a behavioural measure of alpha 2-adrenoceptor sensitivity following acute or chronic administration of tricyclic antidepressants. 2 Chronic (14 day) administration of desipramine (10 mg/kg, i.p.) attenuated the depressant effect of clonidine (20 or 40 microgram/kg) on the startle reflex. 3 No change in response to clonidine was obtained after chronic treatment with two other tricyclic antidepressants, amitriptyline (10 mg/kg) or iprindole (5 mg/kg). 4 Acute administration of these tricyclics (1 h) did not modify the effect of clonidine on startle. 5 It is suggested that the development of alpha 2-adrenoceptor subsensitivity produced by chronic tricyclics may be unique to those compounds, such as desipramine, which are active in blocking the uptake of noradrenaline.

Hydroxylated metabolites of tricyclic antidepressants: preclinical assessment of activity.

Studies investigating a possible relationship between the plasma concentration of tricyclic antidepressants and clinical response have measured only the tertiary and secondary amine forms of these drugs. The present study shows that the hydroxy metabolites of tricyclic antidepressants might also be active. Hydroxylated imipramine, desipramine, chlorimipramine, and nortriptyline inhibit the uptake of norepinephrine and serotonin into synaptosomes to the same extent as do their parent compounds. Hydroxylated nortriptyline and imipramine reverse or prevent reserpine-induced motor retardation and ptosis. Following chronic imipramine, significant steady-state concentrations of unconjugated hydroxylated metabolites are present in rat tissues including the cerebrospinal fluid. Accounting for steady-state concentrations of hydroxylated metabolites of tricyclic antidepressants in man may help to clarify whether there is a relationship between active drug concentration and clinical effect.