Combining bupropion SR with venlafaxine, paroxetine, or fluoxetine: a preliminary report on pharmacokinetic, therapeutic, and sexual dysfunction effects

Review: Bupropion and SSRI-induced side effects

Selective serotonin reuptake inhibitors (SSRIs) are a first line treatment option for millions of patients, due to the positive balance between efficacy and tolerability. However, some side effects associated with their use, can impair quality of life and compliance with treatment. This paper reviews the prevalence of sexual dysfunction, weight gain and emotional detachment during SSRI treatment, the profile of bupropion for each of these events and the ability of bupropion to reverse them. Double-blind trials, open-label trials and anecdotical reports derived from Medline were included. First, there is robust evidence that SSRIs can induce sexual side effects and that bupropion causes less sexual dysfunction than SSRIs. There is limited, mainly open-label evidence that bupropion can reverse SSRI-induced sexual side effects. Second, there is good evidence that long-term treatment with some SSRIs can result in weight gain and that long-term treatment with bupropion can result in a small weight loss. There is only anecdotical evidence that bupropion can reverse SSRI-induced weight gain. Third, treatment with SSRIs has been associated with ;emotional detachment', although controversy exists about this concept. No data are available on the profile of bupropion for ;emotional detachment' or for the reversal of SSRI-induced ;emotional detachment' by bupropion-addition.

Clinical evidence for serotonin and norepinephrine reuptake inhibition of duloxetine

Most antidepressants in clinical use are believed to function by enhancing neurotransmission of serotonin [5-hydroxytryptamine (5-HT)] and/or norepinephrine (NE) via inhibition of neurotransmitter reuptake. Agents that affect reuptake of both 5-HT and NE (serotonin-norepinephrine reuptake inhibitors) have been postulated to offer greater efficacy for the treatment of major depressive disorder (MDD). These dual-acting agents also display a broader spectrum of action, including efficacy for MDD and associated painful physical symptoms, diabetic peripheral neuropathic pain, generalized anxiety disorder, and fibromyalgia syndrome. Substantial preclinical evidence shows that duloxetine, an approved drug for the treatment of MDD, generalized anxiety disorder, and the management of diabetic peripheral neuropathic pain, inhibits reuptake of both 5-HT and NE. This paper reviews clinical and neurochemical evidence of duloxetine's effects on 5-HT and NE reuptake inhibition. The clinical evidence supporting duloxetine's effects on NE reuptake inhibition includes indirect measures such as altered excretion of NE metabolites, cardiovascular effects, and treatment-emergent adverse event profiles similar to those for other drugs believed to act through the inhibition of NE reuptake. In summary, the data presented in this report provide clinical evidence of a mechanism for duloxetine involving both 5-HT and NE reuptake inhibition in humans and are consistent with preclinical evidence for 5-HT/NE reuptake inhibition.

An in vitro mechanistic study to elucidate the desipramine/bupropion clinical drug-drug interaction

There are documented clinical drug-drug interactions between bupropion and the CYP2D6-metabolized drug desipramine resulting in marked (5-fold) increases in desipramine exposure. This finding was unexpected as CYP2D6 does not play a significant role in bupropion clearance, and bupropion and its major active metabolite, hydroxybupropion, are not strong CYP2D6 inhibitors in vitro. The aims of this study were to investigate whether bupropion's reductive metabolites, threohydrobupropion and erythrohydrobupropion, contribute to the drug interaction with desipramine. In human liver microsomes using the CYP2D6 probe substrate bufuralol, erythrohydrobupropion and threohydrobupropion were more potent inhibitors of CYP2D6 activity (K(i) = 1.7 and 5.4 microM, respectively) than hydroxybupropion (K(i) = 13 microM) or bupropion (K(i) = 21 microM). Furthermore, neither bupropion nor its metabolites were metabolism-dependent CYP2D6 inhibitors. Using the in vitro kinetic constants and estimated liver concentrations of bupropion and its metabolites, modeling was able to predict within 2-fold the increase in desipramine exposure observed when coadministered with bupropion. This work indicates that the reductive metabolites of bupropion are potent competitive CYP2D6 inhibitors in vivo and provides a mechanistic explanation for the clinical drug-drug interaction between bupropion and desipramine.

Combined treatment with reboxetine in depressed patients with no response to venlafaxine: a 6-week follow-up study

OBJECTIVE

The purpose of present study was to evaluate the efficacy of the addition of reboxetine in patients that had not previously responded, or had done so only partially, over 6 weeks of conventional pharmacological treatment with venlafaxine.

METHODS

This open-label, prospective and multicentric study included 40 outpatients diagnosed with major depressive disorder according to the DSM-IV criteria. Efficacy was assessed using the 21-item Hamilton Depression Rating Scale (HAMD) and the Clinical Global Impression-Improvement (CGI-I). Safety was evaluated by recording spontaneously reported adverse events. Data were analysed on an intent-to-treat basis, using the last-observation-carried-forward method.

RESULTS

Mean HAMD reduction was 34.9% (P < 0.0001). The percentages of responders (≥50% reduction in HAMD) and patients considered as benefiting from complete remission (HAMD ≤ 10 points) at week 6 were 27.5 and 12.5%, respectively. By the end of the treatment, the score of CGI-I decreased 24.8% (P < 0.0001). Percentage of patient improving (CGI < 4 points) was 47.5%. The most common non-serious adverse events were constipation, nervousness, anxiety and insomnia.

CONCLUSION

These findings suggest that the combined treatment of reboxetine and venlafaxine, in venlafaxine-resistant patients, may be an effective and well-tolerated strategy.

A Critical Overview of the Pharmacologic Management of Treatment-Resistant Depression

Major depressive disorder is a frequent, serious disorder that usually responds partially to treatment and leaves many patients with treatment resistance. This article reviews and critically evaluates the evidence for the management of treatment-resistant depression and examines pharmacologic approaches to alleviate the suffering of patients who benefit insufficiently from initial treatment.

Venlafaxine extended release (XR) in the treatment of panic disorder

Panic disorder is a chronic, recurrent illness, with a lifetime prevalence of about 5%. It is associated with substantial functional impairment, and studies suggest that treatment with medication alone (and no instruction in exposure to feared and avoided situations) is less than optimal. In fact, 40%-90% of patients in long-term follow-up studies in the late 1980s and early 1990s, treated with antidepressants or high potency benzodiazepines alone, remained somewhat symptomatic. Venlafaxine extended release (XR) was effective and well tolerated in both the short-term and long-term treatment of panic disorder. In 12-week trials, venlafaxine XR was significantly more effective than placebo in achieving a panic-free state (54%-70% vs 34%-48%, p Collapse

Key Words

• venlafaxine xr
• panic disorder
• anxiety disorders
• quality of life

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MESH Headings Collapse

Grants Collapse

Affiliation(s)

Kevin Kjernisted University of British Columbia Vancouver, British Columbia, Canada
Diane McIntosh

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The combination of duloxetine and bupropion for treatment-resistant major depressive disorder

Our objective was to assess the effectiveness and safety of the combination of duloxetine and bupropion for treatment-resistant major depressive disorder (TRD). A retrospective chart review was conducted to identify patients with major depressive disorder (MDD) who had not experienced full remission of symptoms following an adequate trial of either duloxetine (n = 3) or bupropion (n = 7), and who then received the combination of these two antidepressants for TRD. Ten patients [37.2 +/- 11.3 years of age, five women, baseline Clinical Global Impressions (CGI) scale score 4.4 +/- 1.1], seven of whom had not remitted following treatment with bupropion (330 +/- 67 mg, 20.5 +/- 12.2 weeks), and three of whom had not remitted following treatment with duloxetine (90 +/- 30 mg, 18 +/- 2 weeks) received at least 4 weeks of combination treatment. The CGI was administered when the combination was first prescribed, and following 8.8 +/- 4.0 (range, 4-16) weeks of treatment. There was a significant decrease in CGI-S (Severity) scores (4.4 +/- 1.1 to 2.1+/-0.9, P <.0001) following combination treatment. Three (30%) patients were remitters at follow-up, and six (60%) were responders who did not achieve full symptom remission. The mean maximum adjunctive duloxetine and bupropion doses were 60.0 +/- 17.3 mg and 175.0 +/- 114.5 mg, respectively. Side effects reported during combination treatment were nausea (n = 2), dry mouth (n = 2), jitteriness/agitation (n = 2), fatigue/drowsiness (n = 2), increased blood pressure (n = 1), increased sweating (n = 1), insomnia (n = 1), pruritus (n = 1), headache (n = 1), sexual dysfunction (n = 1), and weight gain (n = 1). Although preliminary, these results suggest a possible role for the combination of duloxetine and bupropion for TRD.

Current status of augmentation and combination treatments for major depressive disorder: a literature review and a proposal for a novel approach to improve practice

Most patients with major depressive disorder (MDD) do not reach symptom remission. These patients with residual symptoms have worse function and worse prognosis than those who remit. Several augmentation and combination treatments are used to either increase the chances of achieving remission or to eliminate/minimize residual depressive symptoms. Evidence for these pharmacological approaches rests primarily on open, uncontrolled studies, and there are clearly not enough controlled studies. Clinicians should carefully weigh these different treatment options to increase their patients' chances of achieving and sustaining remission from depression. This paper will review the pertinent studies and will propose a novel approach to improve practice involving the use of augmentation or combination strategies at the outset of initial treatment to primarily enhance the chances of remission through synergy and/or a broader spectrum of action. This novel approach could potentially enhance retention and/or increase remission rates since the lack of response with antidepressant monotherapy may lead many depressed patients with little or no benefit to drop out of treatment, precluding the subsequent use of augmentation or combination strategies altogether. In addition, the emergence of certain side-effects (e.g., agitation, insomnia) or the persistence of some initial baseline symptoms (e.g., anxiety, insomnia) may lead to premature discontinuation from monotherapy in the absence of concomitant use of augmenting pharmacological options targeting these symptoms.

A comparison of the efficacy and tolerability of reboxetine and sertraline versus venlafaxine in major depressive disorder: a randomized, open-labeled clinical trial

The aim of the study was to compare the efficacy and tolerability of the combination of reboxetine and sertraline to venlafaxine XR (extended release) in major depressive disorder (MDD). The study consisted of 40 patients with MDD, aged 18-65 years. Patients were evaluated six times during a 10-week period. Treatment was started as venlafaxine XR 75 mg/day once a day (od) or reboxetine 4 mg/day twice a day (bid)+sertraline 50 mg/day od. In the second week, venlafaxine XR was increased to 150 mg/day od and reboxetine 8 mg/day bid while sertraline was kept at the same dose. The Hamilton Depression Rating Scale (HDRS), Montgomery and Asberg Depression Rating Scale, Clinical Global Impressions-Severity of Illness and Clinical Global Impressions-Global Improvement Scale were applied on each visit. Beginning from the second visit, both groups showed significant declines in each scale. There were no significant differences between treatment response rates. Remission rates defined as HDRS<or=10 were significantly higher in the venlafaxine XR group at visit 4 only. However, when remission was accepted as HDRS<or=7, no significant difference was observed. Side effect frequency was similar between the treatment groups. We may suggest that the reboxetine+sertraline combination is not superior to venlafaxine treatment.

Combined antidepressants: clinical experience

OBJECTIVE

To review the current literature on the use of combinations of antidepressive agents.

METHOD

Literature searches were undertaken and reviewed on the use of combinations of antidepressants.

RESULTS

Data sources included surveys, analyses of prescription records, decision algorithms, clinical reports, and studies comparing the monotherapy with combination therapy. More recent surveys recommend combining different selective serotonin reuptake inhibitors (SSRIs), an SSRI plus bupropion or dual action antidepressants plus an SSRI. Decision algorithms recommend an SSRI plus tricyclic antidepressant (TCA) and more recently bupropion plus venlafaxine or mirtazapine. Few controlled clinical trials comparing the combined therapy with monotherapy have been conducted. Beneficial effects have been reported with combinations of TCAs plus mianserin or SSRIs plus mirtazapine.

CONCLUSION

Adding or combining antidepressant medications has advantages for the speed of onset and maintaining the existing response. More rigorous clinical trials comparing combination therapy with monotherapy and for the development of rational treatment guidelines are required.

Dopaminergic-based pharmacotherapies for depression

The serendipitous discovery of the precursors of two of the major contemporary antidepressant families during the late 1950s, iproniazid for the monoamine oxidase inhibitors (MAOIs) and imipramine for the tricyclic antidepressants (TCAs), has guided the subsequent development of antidepressant compounds with predominantly serotonergic, noradrenergic or combined serotonergic and noradrenergic activity. Unfortunately, however, many depressed patients continue to remain symptomatic despite adequate treatment with pharmacologic agents currently available. When one reviews the list of pharmacologic agents currently approved for the treatment of Major Depressive Disorder (MDD), it is apparent that relatively few treatments with dopaminergic activity have been developed to date. Therefore, developing effective antidepressant treatments with pro-dopaminergic properties which also possess a relatively wide safety margin may further improve the standard of care for depression. In the present article we will briefly review studies focusing on the role of dopamine in depression followed by a comprehensive review of pharmacotherapies for depression with pro-dopaminergic activity.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

Sexual function during bupropion or paroxetine treatment of major depressive disorder

OBJECTIVE

The primary objective was to evaluate sexual function (SF) separately in men and women with major depressive disorder (MDD) before and during treatment with bupropion sustained release (SR) or paroxetine. The secondary objectives involved a comparative evaluation of the Sex Effects Scale (Sex FX) and the Investigator-Rated Sexual Desire and Functioning Scale (IRSD-F), as well as a comparison of antidepressant outcomes and an examination of the relation between level of depression and SF over time.

METHOD

There were 141 patients (68 women and 73 men) who met DSM-IV criteria for a current major depressive episode. They were randomly assigned to receive bupropion SR (150 to 300 mg daily) or paroxetine (20 to 40 mg daily) under double-blind trial conditions. Patients were assessed at baseline and at 2, 4, 6, and 8 weeks with the 17-item Hamilton Depression Rating Scale (HDRS17), Sex FX, and IRSD-F.

RESULTS

Prior to treatment, women reported significantly lower SF on both the Sex FX and IRSD-F scales, compared with men. During treatment, there were no significant drug differences on measures of SF over time for women; however, men who were treated with paroxetine reported a worsening of SF, whereas bupropion SR did not significantly alter SF. Both bupropion SR and paroxetine produced clinically and statistically significant reductions in HDRS17 scores as well as comparable rates of response and remission. There was a statistically significant correlation between the 2 measures of SF at all visits. There was also a significant inverse relation between depression and SF in women, but not in men, irrespective of drug.

CONCLUSION

According to the Sex FX scale, a significant difference in antidepressant-related sexual dysfunction was detected in men, but not women, during treatment with bupropion SR or paroxetine.

Use of bupropion in combination with serotonin reuptake inhibitors

Incomplete symptom remission and sexual side effects are common problems for which bupropion often is added to treatment with selective serotonin and serotonin-norepinephrine reuptake inhibitors (SSRIs and SNRIs) for patients with major depressive disorder (MDD). This article reviews the literature on combining bupropion with SSRIs or SNRIs. We used MEDLINE to select studies that included patients diagnosed with MDD treated with any combination of bupropion and an SSRI or SNRI, either to enhance antidepressant response or to ameliorate antidepressant-associated sexual dysfunction. Bibliographies of located articles were searched for additional studies. Controlled and open-label studies support the effectiveness of bupropion in reversing antidepressant-associated sexual dysfunction, whereas open trials suggest that combination treatment with bupropion and an SSRI or SNRI is effective for the treatment of MDD in patients refractory to the SSRI, SNRI, or bupropion alone. The available data suggest that, although not an approved indication, the combination of bupropion and either an SSRI or an SNRI is generally well tolerated, can boost antidepressant response, and can reduce SSRI or SNRI-associated sexual side effects. Additional randomized controlled studies are needed to answer important questions, such as those regarding optimal dose and duration of treatment.

Preclinical and clinical pharmacology of DOV 216,303, a "triple" reuptake inhibitor

DOV 216,303 [(+/-)-1-(3,4-dichlorophenyl)-3-azabicyclo-[3.1.0]hexane hydrochloride] is the prototype of a class of compounds referred to as "triple" reuptake inhibitors. Such compounds inhibit the reuptake of norepinephrine (NE), serotonin (5-HT), and dopamine (DA), the three neurotransmitters most closely linked to major depressive disorder. DOV 216,303 inhibits [(3)H]NE, [(3)H]5-HT, and [(3)H]DA uptake to the corresponding human recombinant transporters (expressed in HEK 293 cells) with IC(50) values of approximately 20, 14, and 78 nM, respectively. DOV 216,303 is active in tests predictive of antidepressant activity including the mouse forced swim test and reversal of tetrabenazine-induced ptosis and locomotor depression. The pharmacodynamic, pharmacokinetic, and toxicological profile of DOV 216,303 in animals prompted us to initiate clinical studies. In both single and multiple dose studies using normal volunteers, DOV 216,303 was safe and well-tolerated. Furthermore, both C(max) and AUC values were dose-proportional between 5-150 mg. The plasma concentrations of DOV 216,303 at doses >10 mg were in excess of the IC(50) values for inhibition of biogenic amine reuptake. In a Phase II study designed to explore the safety and tolerability of DOV 216,303 in depressed individuals, patients received either 100 mg DOV 216,303 (50 mg b.i.d.) or 40 mg citalopram (20 mg, b.i.d.) for two weeks. A placebo arm was not employed in this study because several institutional review boards required administration of an active control to severely depressed individuals. Time dependent reductions in HAM-D scores (the primary outcome measure) were observed in both the DOV 216,303 and citalopram groups compared to baseline scores (p < 0.0001). The side effect profile was not remarkably different between treatment arms. These findings provide preliminary evidence of a clinically meaningful antidepressant action with a molecule capable of inhibiting the three transmitters most closely linked to major depressive disorder.

The safety of non-stimulant agents for the treatment of attention-deficit hyperactivity disorder

Due to their well-established efficacy and safety, stimulants are the drugs of first choice if medication for attention-deficit hyperactivity disorder (ADHD) is required. Nevertheless, for some individuals other, non-stimulant treatments are needed for several reasons. If so, atomoxetine is recommended as a second-line treatment. In addition, several tricyclic antidepressants, such as desipramine or imipramine, as well as alpha-2 agonists, especially clonidine or bupropion, might be efficient in treating ADHD, in particular in specific co-morbid conditions. Despite the fact that non-stimulant treatments in ADHD are usually well-tolerated with side effects being mostly moderate and transient, special safety aspects and precautions, specific for each drug, have to be considered whenever a non-stimulant treatment is chosen. This review focuses on the tolerability, occurrence of adverse events, precautions required to prevent severe adverse events, and essential pharmacological interaction in the treatment of ADHD symptoms by non-stimulants.

To combine or not to combine? A literature review of antidepressant combination therapy

OBJECTIVE

Treatment resistant depression is a common clinical problem and a major public health concern. The use of antidepressant combinations to overcome treatment resistance, while somewhat controversial, is a popular strategy in practice. This paper reviews published trials on combination antidepressants with a view to inform clinical practice.

METHOD

A systematic but selective review of the published literature was conducted using EMBASE, PSYCHLIT and MEDLINE with relevant search terms.

RESULTS

A number of trials suggesting efficacy of combination antidepressants were found. These are incorporated into a number of treatment guidelines for the management of treatment refractory depression. Clinicians should be cautious regarding pharmacokinetic and pharmacodynamic interactions, including the serotonin syndrome, however combination strategies are an effective option.

CONCLUSIONS

Many antidepressants can be usefully combined especially if they engage separate mechanisms of action. Clinically, antidepressant combinations provide a useful resort in otherwise treatment resistant individuals. However, much further research is needed to determine relative efficacy and determine long term outcome.

Bupropion for major depressive disorder: Pharmacokinetic and formulation considerations

BACKGROUND

Major depressive disorder (MDD) is a common psychiatric condition, with 6.6% of the adult population in the United States experiencing a major depressive episode during any given year. Depressed patients must receive adequate treatment to maximize the likelihood of clinical success. Bupropion hydrochloride, a noradrenergic/dopaminergic antidepressant, is available in 3 oral formulations: immediate release (IR) (given TID), sustained release (SR) (given BID), and extended release (XL) (given QD). Understanding the pharmacokinetic (PK) properties and formulations of bupropion can help optimize clinical use.

OBJECTIVES

: The aims of this article were to provide a review of the PK properties of bupropion and identify its various formulations and clinical applications to help optimize treatment of MDD.

METHODS

: In this review, data concerning PK trials/reports were collected from articles identified using a PubMed search. The search was conducted without date limitations and using the search terms bupropion, bupropion SR, bupropion XL, bupropion pharmacokinetics, bupropion metabolism, and bupropion drug interactions. Additional reports were selected from references that appeared in articles identified in the original search. In addition, data from studies summarized in product information and labeling were obtained. All available information, concentrating on studies in humans, pertinent to bupropion PK properties and/or formulations was included.

RESULTS

: Bupropion is extensively metabolized by the liver (t(1/2), approximately 21 hours). Hydroxybupropion, the primary active metabolite (t(1/2), approximately 20 hours), is formed by cytochrome P450 (CYP) 2B6. At steady state, C(max) of hydroxybupropion is 4- to 7-fold higher, and the AUC is approximately 10-fold greater, compared with those of the parent drug. Threohydrobupropion and erythrohydrobupropion (mean [SD] t(1/2) values, approximately 37 [13] and approximately 33 [10] hours, respectively), the other active metabolites of bupropion, are formed via nonmicrosomal pathways. Relative to bupropion, the C(max) values are approximately 5-fold greater for threohydrobupropion and similar for erythrohydrobupropion. Based on a mouse antitetrabenazine model, hydroxybupropion is approximately 50% as active as bupropion, and threohydrobupropion and erythrohydrobupropion are approximately 20% as active as bupropion. Bupropion lowers the seizure threshold and, therefore, concurrent administration with other agents that lower the seizure threshold should be undertaken cautiously. Potential interactions with other agents that are metabolized by CYP2B6 should be considered. In addition, bupropion inhibits CYP2D6 and may reduce clearance of agents metabolized by this enzyme. Absorption of the XL formulation is prolonged compared with the IR and SR formulations (T(max), approximately 5 hours vs approximately 1.5 and approximately 3 hours, respectively). Bupropion is dosed without regard to food.

CONCLUSIONS

: Understanding the PK profile and formulations of bupropion can help optimize clinical use. Bupropion is metabolized extensively, resulting in 3 active metabolites. This metabolic profile, various patient factors (eg, age, medical illnesses), and potential drug interactions should be considered when prescribing bupropion. The 3 formulations-bupropion, bupropion SR, and bupropion XL-are bioequivalent and offer options to optimize treatment for patients with MDD.

The dosing of atypical antipsychotics

Drug-drug interactions or genetic variability may require using doses different from those recommended for atypical antipsychotics. Dosage alterations of olanzapine and clozapine, dependent on cytochrome P450 1A2 (CYP1A2) for clearance, and quetiapine, dependent on cytochrome P450 3A (CYP3A), may be necessary when used with other drugs that inhibit or induce their metabolic enzymes. Smoking cessation can significantly increase clozapine, and perhaps olanzapine, levels. Ziprasidone pharmacokinetic drug-drug interactions are not likely to be important. Genetic variations of cytochrome P450 2D6 (CYP2D6) and drug-drug interactions causing inhibition (CYP2D6 and/or CYP3A) or induction (CYP3A) may be important for risperidone, and perhaps for aripiprazole, dosing. Adding inhibitors may cause side effects more easily in drugs with a narrow therapeutic window, such as clozapine or risperidone, than in those with a wide therapeutic window, such as olanzapine or aripiprazole. Adding inducers may be associated with a gradual development of lost efficacy.

Depression and renal disease

Major depressive disorder (MDD) is a highly prevalent disease, frequently characterized by recurrent or chronic course, and by comorbidity with other medical illnesses. The lifetime prevalence of MDD ranges up to 17% in the general population, and it almost doubles in patients with diabetes (9-27%), stroke (22-50%), or cancer (18-39%). Moreover, MDD worsens the prognosis, quality of life, and treatment compliance of patients with comorbid medical illnesses. Similar to what is observed with other comorbid illnesses, MDD worsens the outcome of kidney disease patients by increasing both morbidity and mortality. Treatment of depressive symptoms in renal failure patients increases medication acceptability and therefore potentially improves the overall patient outcome. The issue of the safety of antidepressant treatment in subjects with renal failure is frequently counterbalanced by the risks associated with depression comorbidity, provided that antidepressants with a low volume of distribution and low protein binding are prescribed, and most important, at low initial doses. Screening for CYP isoenzyme interactions with current medications is also recommended before starting antidepressant treatment.

Conversion from sustained-release to immediate-release bupropion: patient tolerability and economic impact

STUDY OBJECTIVE

To assess patient tolerability and impact on institutional drug acquisition costs of converting patients from sustained-release bupropion to generic immediate-release bupropion.

DESIGN

Retrospective medical record review.

SETTING

Veterans Affairs medical center.

PATIENTS

One hundred three outpatients who had been receiving sustained-release bupropion and were converted to immediate-release bupropion at equal individual doses and frequencies.

MEASUREMENTS AND MAIN RESULTS

Medical records were reviewed for documentation of adverse effects thought to be associated with bupropion treatment; reports of seizure occurrence were specifically sought. Patterns of bupropion dosing were also assessed. Institutional drug acquisition costs were evaluated by comparing actual costs of bupropion for each patient before and after conversion. Adverse effects reported with immediate-release bupropion were those commonly associated with this drug (headache, agitation, chest pain, and gastrointestinal complaints) and were neither unusually frequent nor severe. No seizures were reported after the drug conversion. Mean daily doses of bupropion were not significantly different after conversion. Mean single doses of immediate-release bupropion were below 150 mg; however, six patients did receive single doses of 200 mg. After conversion, the annual institutional drug acquisition cost for bupropion decreased by approximately $48,910.

CONCLUSION

Conversion from sustained-release bupropion to immediate-release bupropion appears to be safe. Single 200-mg doses of immediate-release bupropion can apparently be administered to some patients without inducing excessive adverse effects, including seizures. Marked reduction in drug acquisition costs can be achieved with this conversion.

Phosphodiesterase 5 inhibitors for erectile dysfunction

OBJECTIVE

To review the pharmacologic and clinical trial data of the Food and Drug Administration-approved phosphodiesterase 5 (PDE5) inhibitors for the treatment of erectile dysfunction (ED).

DATA SOURCES

Primary research and review articles were identified through a search of ScienceDirect, PubMed/MEDLINE, and International Pharmaceutical Abstracts (1990-August 2004). The following search terms were used in the Medicine Dentistry and Pharmacology, Toxicology, and Pharmaceutical Sciences subcategories: phosphodiesterase 5 inhibitor, PDE5 inhibitor, erectile dysfunction, sildenafil, vardenafil, tadalafil, prostatectomy, and diabetes. Web of Science (1990-August 2004) was used to search for additional abstracts using the same search terms as above. The package inserts for sildenafil, vardenafil, and tadalafil were also consulted.

STUDY SELECTION AND DATA EXTRACTION

All identified research, review articles, and abstracts were assessed for relevance, and all relevant information was included. Priority was given to the primary medical literature and clinical trial reports.

DATA SYNTHESIS

ED is a common disorder in males with increased prevalence associated with age and presence of cardiovascular disease, prostatectomy, or diabetes mellitus. Sildenafil, vardenafil, and tadalafil are selective PDE5 inhibitors currently available for treatment of ED. Their pharmacology and pharmacokinetics vary slightly, but with potentially important clinical differences in duration of activity; all have similar clinical efficacy and adverse effect profiles in patients with ED of various causes.

CONCLUSIONS

Sildenafil, vardenafil, and tadalafil are safe and effective PDE5 inhibitors for the treatment of ED.

Inhibition of CYP2D6 activity by bupropion

The purpose of this study was to assess the effect of bupropion on cytochrome P450 2D6 (CYP2D6) activity. Twenty-one subjects completed this repeated-measures study in which dextromethorphan (30-mg oral dose) was administered to smokers at baseline and after 17 days of treatment with either bupropion sustained-release (150 mg twice daily) or matching placebo. Subjects quit smoking 3 days before the second dextromethorphan administration. To assess CYP2D6 activity, urinary dextromethorphan/dextrorphan metabolic ratios were calculated after an 8-hour urine collection. Thirteen subjects received bupropion, and 8 received placebo. In those receiving active medication, the dextromethorphan/dextrorphan ratio increased significantly at the second assessment relative to the first (0.012 +/- 0.012 vs. 0.418 +/- 0.302; P < 0.0004). No such change was observed in those randomized to placebo (0.009 +/- 0.010 vs. 0.017 +/- 0.015; P = NS). At baseline, all subjects were phenotypically extensive CYP2D6 metabolizers (metabolic ratio <0.3); after treatment, 6 of 13 subjects receiving bupropion, but none of those receiving placebo, had metabolic ratios consistent with poor CYP2D6 metabolizers. Bupropion is therefore a potent inhibitor of CYP2D6 activity, and care should be exercised when initiating or discontinuing bupropion use in patients taking drugs metabolized by CYP2D6.

Co-prescription of cytochrome P450 2D6/3A4 inhibitor-substrate pairs in clinical practice. A retrospective analysis of data from Norwegian primary pharmacies

OBJECTIVE

Inhibition of cytochrome P (P450) (CYP) enzymes, in particular CYP3A4 and CYP2D6, is an important drug-interacting mechanism. The objective of our study was to assess how frequently CYP3A4 and CYP2D6 inhibitors are co-prescribed with substrates of the respective enzymes.

METHODS

Included inhibitors were clarithromycin, erythromycin, fluconazole, itraconazole, ketoconazole and nefazodone (CYP3A4 inhibitors) and bupropion, fluoxetine, paroxetine and terbinafine (CYP2D6 inhibitors). The inhibitors were combined with substrates shown to be pharmacokinetically sensitive towards inhibition (190 drug pairs in total). Lists of patients receiving inhibitors and substrates were drawn from prescription databases (approximately 43,500 patients) of three Norwegian primary pharmacies during a 6-month period (July 2002 to January 2003). The lists were matched on name and date of birth to identify patients using drug pairs. Concurrent use was made probable from dates of purchase and drug profiles.

RESULTS

Inhibitors were prescribed to 2,062 patients. Altogether, 369 events of substrate co-prescription were registered. The highest frequencies of co-prescribed substrates were found for paroxetine (101 events per 267 patients, 38%), fluoxetine (36 events per 110 patients, 33%) and clarithromycin (59 events per 242 patients, 24%). The drugs most often detected in combination with inhibitors were codeine (116 events) and metoprolol (38 events) for CYP2D6 and zopiclone (45 events) and simvastatin (26 events) for CYP3A4.

CONCLUSION

Several commonly used CYP2D6 and CYP3A4 inhibitors are frequently co-prescribed with substrates in Norwegian clinical practice. Alertness when inhibitors are prescribed would aid physicians and pharmacists to detect many drug combinations with potential interaction risk.

Therapeutic alternatives for difficult-to-treat depression: a narrative review of the state of the evidence

Despite the large number of depressed patients who do not respond to first-line antidepressants, the evidence base of alternate strategies is quite thin. In this article, a simple 5-stage system for categorizing treatment-resistant depression (TRD) is described and the evidence pertaining to the major strategies currently utilized is summarized using four grades, ranging from D (case reports only) to A (multiple positive placebo-controlled trials). It is concluded that the level of evidence supporting many of the contemporary strategies used for TRD (eg, combinations of antidepressants and augmentation with medications such as pindolol, buspirone, or modafinil) is scanty at best. Even the fundamental question concerning "to augment or to switch" is not answerable with available data. It is noted that the best-documented treatments (ie, lithium augmentation, switching to a monoamine oxidase inhibitor, and electroconvulsive therapy) are among the least utilized. This state of affairs will improve with completion of the studies of Systematic Treatment Alternatives to Relieve Depression, a large multicenter study of difficult-to-treat depression funded by the National Institute of Mental Health. There is a need for greater collaboration among academicians and organizations, such as the American Psychiatric Association, the National Institute of Mental Health, and the pharmaceutical industry, to ensure that sufficient research is conducted so that clinician's choices for patients with TRD can be guided by empirical evidence.

Elevated Defibrillation Threshold with Venlafaxine Therapy

Depression is a common comorbidity in patients with heart failure or implantable cardioverter-defibrillators (ICDs). A 35-year-old woman with depression, nonischemic cardiomyopathy, and a history of cardiac arrest had an ICD implanted. During initial testing, the device failed to internally defibrillate the patient. Venlafaxine, an antidepressant with cardiac sodium channel blocking activity, was identified as a potential contributor to her elevated defibrillation threshold. After the venlafaxine was discontinued, the ICD was able to successfully internally defibrillate the patient. Clinicians should be aware of this potential adverse drug-device interaction. Further studies are needed to determine the clinical significance of venlafaxine therapy in patients with ICDs.

Reboxetine adjunct for partial or nonresponders to antidepressant treatment

BACKGROUND

To investigate the usefulness of the combination therapy with two antidepressants from different pharmacological families in treatment-resistant depressive patients.

METHODS

In this prospective 6 weeks open-label study, we assessed the effectiveness of the addition of reboxetine to 61 depressive patients that had previously not responded, or had done so only in a partial way, to conventional treatment, in monotherapy, with selective serotonin reuptake inhibitors (SSRIs), venlafaxine or mirtazapine. Data were analyzed on an intent-to-treat basis, using the last-observation-carried-forward (LOCF) method.

RESULTS

Mean decrease on the 21-item Hamilton Depression Rating Scale (HDRS) score was 48.9% and on the Clinical Global Impressions Scale (CGI), 38.9%. At the end of the treatment, 62.3% of the patients were evaluated as improvement (CGI < 4), 54.1% as responders (HDRS < or = 50%) and 45.9% in remission (HDRS < or = 10). No serious side effects were observed during combination therapy, being more frequent increased sweating (8.2%) and dry mouth (6.6%).

CONCLUSIONS

These findings suggest that the strategy of combination with reboxetine may be an effective and well-tolerated tool in treatment-resistant patients who have failed to adequately respond to monotherapy with SSRIs, venlafaxine or mirtazapine.

Preclinical models of sexual desire: conceptual and behavioral analyses

The epidemiology, etiology and proposed treatments for the sexual desire disorders are briefly reviewed before turning to an analysis of preclinical models. We suggest that the concept of sexual desire in the human is equivalent to sexual motivation as employed in the scientific literature. Many animal tests for sexual motivation have been described over the years. Most of them are based on the evaluation of the rate or speed of performing learned operant responses. These are not ideal measures for inferring the intensity of sexual motivation. We present a test for sexual incentive motivation, which has been used in male and female rats. No learning is involved, and the test is rather insensitive to variations in ambulatory activity and it does not employ rate measures. A procedure that recently has attracted much attention, paced-mating behavior in the female, does not seem to be as useful as could be expected. In fact, it does not appear to be superior to tests for sexual receptivity (lordosis). The lack of established, clinically efficient treatments for sexual desire disorders makes it difficult to evaluate if any model has predictive validity. However, the model proposed here may be isomorphic and homologous to the human condition.

Bupropion sustained release for the treatment of hypoactive sexual desire disorder in premenopausal women

Premenopausal women meeting operational criteria for idiopathic, acquired, global hypoactive sexual desire disorder were studied in a randomized, double-blind, placebo-controlled, multiple-site escalating dose 112-day trial of bupropion sustained release. Outcome was measured by investigator-rating and self-administered questionnaires. All measures indicated greater sexual responsiveness in women receiving bupropion. The Changes in Sexual Functioning Questionnaire indicated that bupropion had significant effects on increasing measures of sexual arousal, orgasm completion, and sexual satisfaction.

A Review of the Neuropharmacology of Bupropion, a Dual Norepinephrine and Dopamine Reuptake Inhibitor

BACKGROUND: The neurochemical and biological effects of antidepressant medications have become better defined over the last decade. When the anti-depressant bupropion was introduced in the United States in 1989, the specific pharmacologic basis of its clinical effects was uncertain. Research conducted over the past decade has significantly advanced the understanding of the neuropharmacology of bupropion and has demonstrated a novel mechanism of antidepressant activity. This article discusses the mechanism of action of bupropion and relates the drug's neuropharmacologic effects to its clinical efficacy and tolerability profiles. DATA SOURCES: Data were obtained via the MEDLINE database in an English-language search spanning the period 1965 to May 2002 and using the search terms bupropion, bupropion SR, and antidepressants, as well as from the manufacturer's bupropion databases. CONCLUSIONS: The preclinical and clinical data show that bupropion acts via dual inhibition of norepinephrine and dopamine reuptake and is devoid of clinically significant serotonergic effects or direct effects on postsynaptic receptors. Dual norepinephrine and dopamine reuptake inhibition is associated with a unique clinical profile. Bupropion has demonstrated efficacy comparable to that of other antidepressants. However, because bupropion is a selective norepinephrine and dopamine reuptake inhibitor with no serotonergic activity, common antidepressant-associated side effects, such as sexual dysfunction, weight gain, and sedation, are not associated with bupropion therapy.

Bethanecol chloride for treatment of clomipramine-induced orgasmic dysfunction in males

PURPOSE: To investigate whether bethanecol chloride may be an alternative for the clinical management of clomipramine-induced orgasmic dysfunction, reported to occur in up to 96% of male users. METHODS: In this study, 12 fully remitted panic disorder patients, complaining of severe clomipramine-induced ejaculatory delay, were randomly assigned to either bethanecol chloride tablets (20 mg, as needed) or placebo in a randomized, double-blind, placebo-controlled, two-period crossover study. A visual analog scale was used to assess severity of the orgasmic dysfunction. RESULTS: A clear improvement was observed in the active treatment period. No placebo or carry-over effects were observed. CONCLUSION: These findings suggest that bethanecol chloride given 45 minutes before sexual intercourse may be useful for clomipramine-induced orgasmic dysfunction in males.

Achieving long-term optimal outcomes in geriatric depression and anxiety

Depression and anxiety disorders are very common in the elderly. Data accumulated over the past 2 decades have shown that most older patients can tolerate and respond to acute treatment with serotonergic antidepressants, other psychotropic agents, or manual-based psychotherapy. However, outcomes under usual-care conditions remain poor. This review proposes that clinicians may significantly improve the long-term outcomes of their older patients with depression and anxiety by focusing on four key factors: (1) identification and treatment of comorbid conditions; (2) full remission of acute symptoms; (3) education of patients, families, and professional colleagues about the need for long-term treatment; and (4) prevention and management of medication side-effects.

Selective serotonin reuptake inhibitors combined with venlafaxine in depressed patients who had partial response to venlafaxine: four cases

One third of depressive patients show partial or no response to antidepressant treatment. With partial or nonresponders, treatment strategies are as follows: switching to another antidepressant, augmenting with other psychotropic agents, or combining antidepressants. There are no data in the literature about the positive effect of combining venlafaxine with selective serotonin reuptake inhibitors (SSRIs). In this report, the presented cases had been on at least two different classes of antidepressant medication (or combination of antidepressants) for an adequate time and dose. They showed only a partial response to high dose of venlafaxine but improved after the addition of an SSRI (sertraline, citalopram, or paroxetine) to venlafaxine. The combination treatment was well tolerated in all of the cases.

Pharmacologic management of sexual dysfunction: benefits and limitations

What is the current knowledge concerning the pharmacologic treatment of human sexual dysfunction? A number of interventions, including oral phophodiesterase inhibitors and intracorporeal agents with vasodilatory effects, are available to treat male erectile disorder. Serotonergic drugs have been shown to be effective in the treatment of rapid ejaculation. Various lines of research suggest that high dosages of androgenic agents may eventually have a role in the treatment of decreased libido in females. There may be a role for phophodiesterase inhibitors in the treatment of a subgroup of women with arousal disorders. Normal sexual function involves successful integration of biological, psychological, and interpersonal influences. Clinical psychiatry with its biopsychosocial model should incorporate the treatment of human sexual dysfunction within its purview.

Selective phosphodiesterase type-5 inhibitor treatment of serotonergic reuptake inhibitor antidepressant-associated sexual dysfunction: a review of diagnosis, treatment, and relevance

Sexual dysfunction related to antidepressants, particularly serotonin reuptake inhibitors is a major cause of premature treatment discontinuation. This places patients at increased risk for recurrence, relapse, chronicity, and mortality (eg, suicide). The clinical assessment requires a comprehensive evaluation of sexual function, including libido, arousal, orgasm, and resolution prior to affective disorder, disturbances associated with the emergence of depression, and changes or dysfunctions associated with antidepressant treatment. Other factors to be included for evaluating sexual dysfunction include inquiry for concurrent medical conditions, somatic treatments, lifestyle risk factors, and response to antidepressants. Current treatment approaches to antidepressant-associated sexual dysfunction have relied on open-label reports, literature reviews, and clinical wisdom. Without double-blind, placebo-controlled studies to support them, too much non-evidence-based treatment may be offered to patients. Advances into nonadrenergic-noncholinergic novel signal transduction, specifically phosphodiesterase type-5 inhibitors, offer new opportunities for developing evidence-based treatments for this side effect and improving depression disease management outcomes.