Overdose and safety with fluvoxamine

Sigma-1 receptor and seizures

Over the last decade, sigma-1 receptor (Sig1R) has been recognized as a valid target for the treatment of seizure disorders and seizure-related comorbidities. Clinical trials with Sig1R ligands are underway testing therapies for the treatment of drug-resistant seizures, developmental and epileptic encephalopathies, and photosensitive epilepsy. However, the direct molecular mechanism by which Sig1R modulates seizures and the balance between excitatory and inhibitory pathways has not been fully elucidated. This review article aims to summarize existing knowledge of Sig1R and its involvement in seizures by focusing on the evidence obtained from Sig1R knockout animals and the anti-seizure effects of Sig1R ligands. In addition, this review article includes a discussion of the advantages and disadvantages of the use of existing compounds and describes the challenges and future perspectives on the use of Sig1R as a target for the treatment of seizure disorders.

Guidelines for choice of selective serotonin reuptake inhibitor in depressive illness

The selective serotonin reuptake inhibitors (SSRIs) are the most extensively studied of the newer antidepressants and are increasingly being used as first-line treatment for depression (Anderson et al, 2000). In this article we concentrate on issues that need to be taken into account when selecting one of the five SSRIs marketed in the UK (citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline) for individual patients. We have concentrated on treatment of depression and have not reviewed their use in anxiety disorders because comparative data are lacking.

Newer v. older antidepressants in long-term pharmacotherapy: Revisiting… Prevention of relapse and recurrence of depression

There is much evidence from clinical trials that antidepressants help prevent relapse and recurrence of major depression. However, this is unlikely to hold true for all patients with depression, particularly those treated in primary care. Individual antidepressants are equally efficacious, so choice (as first-line treatment in general or for individual patients) is largely determined by differences in side-effects, even though many of these disappear during long-term treatment, owing to adaptation. Specific effects that are considered in choosing a drug include those on cognition, psychomotor performance and sexual function; drug interactions, lethality in overdose and the potential for teratogenicity are also considered. There are insufficient entirely objective and generally accepted data on pharmaco-economics to allow for confident recommendations on drug choice for long-term treatment. Drug acquisition costs must be considered by those with restricted budgets, and especially patients in developing countries where difference in cost between newer and older drugs can be translated into more food for a hungry family.

Selective serotonin reuptake inhibitor poisoning: An evidence-based consensus guideline for out-of-hospital management

A review of US poison center data for 2004 showed over 48,000 exposures to selective serotonin reuptake inhibitors (SSRIs). A guideline that determines the conditions for emergency department referral and prehospital care could potentially optimize patient outcome, avoid unnecessary emergency department visits, reduce health care costs, and reduce life disruption for patients and caregivers. An evidence-based expert consensus process was used to create the guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the lead author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial management of patients with a suspected ingestion of an SSRI by 1) describing the process by which an ingestion of an SSRI might be managed, 2) identifying the key decision elements in managing cases of SSRI ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to ingestion of immediate-release forms of SSRIs alone. Co-ingestion of additional substances might require different referral and management recommendations depending on their combined toxicities. This guideline is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment. Recommendations are in chronological order of likely clinical use. The grade of recommendation is in parentheses. 1) All patients with suicidal intent, intentional abuse, or in cases in which a malicious intent is suspected (e.g., child abuse or neglect) should be referred to an emergency department. This activity should be guided by local poison center procedures. In general, this should occur regardless of the dose reported (Grade D). 2) Any patient already experiencing any symptoms other than mild effects (mild effects include vomiting, somnolence [lightly sedated and arousable with speaking voice or light touch], mydriasis, or diaphoresis) should be transported to an emergency department. Transportation via ambulance should be considered based on the condition of the patient and the length of time it will take the patient to arrive at the emergency department (Grade D). 3) Asymptomatic patients or those with mild effects (defined above) following isolated unintentional acute SSRI ingestions of up to five times an initial adult therapeutic dose (i.e., citalopram 100 mg, escitalopram 50 mg, fluoxetine 100 mg, fluvoxamine 250 mg, paroxetine 100 mg, sertraline 250 mg) can be observed at home with instructions to call the poison center back if symptoms develop. For patients already on an SSRI, those with ingestion of up to five times their own single therapeutic dose can be observed at home with instructions to call the poison center back if symptoms develop (Grade D). 4) The poison center should consider making follow-up calls during the first 8 hours after ingestion, following its normal procedure. Consideration should be given to the time of day when home observation will take place. Observation during normal sleep hours might not reliably identify the onset of toxicity. Depending on local poison center policy, patients could be referred to an emergency department if the observation would take place during normal sleeping hours of the patient or caretaker (Grade D). 5) Do not induce emesis (Grade C). 6) The use of oral activated charcoal can be considered since the likelihood of SSRI-induced loss of consciousness or seizures is small. However, there are no data to suggest a specific clinical benefit. The routine use of out-of-hospital oral activated charcoal in patients with unintentional SSRI overdose cannot be advocated at this time (Grade C). 7) Use intravenous benzodiazepines for seizures and benzodiazepines and external cooling measures for hyperthermia (>104 degrees F [>40 degrees C]) for SSRI-induced serotonin syndrome. This should be done in consultation with and authorized by EMS medical direction, by a written treatment protocol or policy, or with direct medical oversight (Grade C).

Clinical pharmacokinetics of sertraline

Sertraline is a naphthalenamine derivative with the predominant pharmacological action of inhibiting presynaptic reuptake of serotonin from the synaptic cleft. It was initially marketed for the treatment of major depressive disorder and is now approved for the management of panic disorder, obsessive-compulsive disorder and post-traumatic stress disorder. Sertraline is slowly absorbed following oral administration and undergoes extensive first-pass oxidation to form N-desmethyl-sertraline, a weakly active metabolite that accumulates to a greater concentration in plasma than the parent drug at steady state. Sertraline is eliminated from the body by other metabolic pathways to form a ketone and an alcohol, which are largely excreted renally as conjugates. The elimination half-life of sertraline ranges from 22-36 hours, and once-daily administration is therapeutically effective. Steady-state plasma concentrations vary widely, up to 15-fold, in patients receiving usual antidepressant dosages between 50 and 150 mg/day. However, only sparse data have been published that support useful correlations between sertraline plasma concentrations and therapeutic or adverse effects to justify therapeutic drug monitoring. Sertraline has minimal inhibitory effects on the major cytochrome P450 enzymes, and few drug-drug interactions of clinical significance have been documented. Like other selective serotonin reuptake inhibitors, sertraline is well tolerated in therapeutic dosages and relatively safe in overdosage.

Fluvoxamine as effective as clomipramine against symptoms of severe depression: results from a multicentre, double-blind study

BACKGROUND

Although selective serotonin reuptake inhibitors (SSRIs) are better tolerated than tricyclic antidepressants, their efficacy in severe depression remains to be further elucidated.

METHOD

A double-blind, multicentre study was conducted in 86 severely depressed inpatients (>or= 25 on the 17-item Hamilton depression rating scale [HAMD] total score) to compare the efficacy and safety of fluvoxamine with that of clomipramine. Following placebo run-in, 86 patients were randomised to receive fluvoxamine or clomipramine (100-250 mg/day) for 8 weeks.

RESULTS

Fluvoxamine and clomipramine both resulted in marked improvements; there were no statistically significant differences between them on the 17-item HAMD total score, the clinical global impression severity of illness or global improvement items or the Montgomery-Asberg depression rating scale, at any visit. At the end of the study, 71% in the fluvoxamine group and 69% in the clomipramine group were responders (>or= 50% decrease in 17-item HAMD total score). However, fluvoxamine was better tolerated than clomipramine. Clomipramine was associated with a higher incidence of overall and treatment-related adverse events. In addition, the percentage of patients discontinued prematurely due to adverse events was more than twice as high with clomipramine than with fluvoxamine (24% vs 11%).

CONCLUSION

Fluvoxamine and clomipramine are equally effective in severe depression, but fluvoxamine has a better safety and tolerability profile.

Depression and the dying older patient

Depression remains a source of considerable suffering among dying older adults. Unfortunately, clinical depression commonly is overlooked in this vulnerable population and often goes untreated. An overview of diagnosing depression in older patients is presented. Various risk factors for depression in the palliative care setting are examined. The somatic therapies that are available for treatment consideration in older, depressed adults nearing death are reviewed.

Citalopram overdose--review of cases treated in Swedish hospitals

BACKGROUND

The toxic effects of acute citalopram overdose are reported by the Swedish Poisons Information Centre.

DESIGN

Case reports received from Swedish hospitals during 1995 have been analyzed. Forty-four cases of pure citalopram intoxication have been studied in detail.

RESULTS

At doses below 600 mg, mild symptoms were observed. Doses above 600 mg caused ECG abnormalities and convulsions in some patients, while doses greater than 1900 mg caused such symptoms in all patients.

CONCLUSIONS

The findings are consistent with previous reports claiming that selective serotonin reuptake inhibitors are less toxic compared to tricyclic antidepressants. However, there is a risk of developing serious symptoms when large doses have been ingested.

How safe are serotonin reuptake inhibitors for depression in patients with coronary heart disease?

Depression occurs frequently in patients with coronary heart disease (CHD), and confers significant risk for additional morbidity and mortality. The cardiac effects of the tricyclic antidepressants (TCAs) have been well characterized. In contrast, the cardiac effects of the selective serotonin reuptake inhibitors (SSRIs) have been less thoroughly investigated. The Medline database from 1986 to 1996 was searched for all reports of cardiac effects of SSRIs, and this literature is summarized. In addition, potential drug interactions, reports of side effects, and efficacy studies in the elderly are reviewed. Finally, recommendations are made considering the risk/benefit ratio.

Pharmacokinetics of selective serotonin reuptake inhibitors: clinical relevance

Selective serotonin reuptake inhibitors (SSRIs) are a safe and effective class of drugs for treatment of depressive and obsessive-compulsive disorders. Among this class of drugs, pharmacodynamic actions, antidepressant efficacy and adverse effect profiles are remarkably similar. However, pharmacokinetic profiles of SSRIs are substantially different especially with respect to pharmacokinetically mediated drug-drug interactions. For example, fluoxetine and paroxetine produce clinically significant inhibition of cytochrome P450 2D6 at their usually effective antidepressant dose, whereas citalopram, fluvoxamine or sertraline do not. There is also a substantial difference between SSRIs with respect to their capacity to inhibit other cytochrome P450 enzymes including IA2, 2C19, 3A4 and possibly 2C9/10. The inhibition of these enzymes can reduce the clearance of concomitantly administered drugs which are dependent on oxidative metabolism mediated by these enzymes as a necessary prerequisite for their subsequent elimination. The accumulation of unusually high levels of such drugs can result in an increase in nuisance and/or more serious, even life-threatening, adverse effects depending on the pharmacology of the co-prescribed drug. Knowledge of these issues will enable clinicians to predict and make appropriate dose adjustments to avoid potential drug-drug interactions that otherwise could result in toxicity.

Comparative safety and tolerability of selective serotonin reuptake inhibitors

The selective serotonin reuptake inhibitors (SSRIs) have the best established tolerance and safety profile of the available antidepressants. Evidence for this conclusion comes from controlled clinical trials, post-marketing surveillance, prescription audits and case reports. Comparative studies are sparse within the class of SSRIs, and methodological differences between studies are problematic, yet certain differences emerge in tolerability when comparing placebo-adjusted incidence rates for the most common adverse events. Fluoxetine commonly produces nervousness, anxiety, insomnia and headache. Sexual dysfunction is more common with sertraline. Dry mouth can occur from paroxetine, and gastrointestinal effects (cramps, diarrhoea) from sertraline. The incidence of nausea appears to be no greater for any particular drug, especially after several weeks of treatment. Hyponatraemia and extrapyramidal side effects are rare events reported with all SSRIs. General guidelines are given for choosing an initial SSRI according to adverse effect profile; however, inter-subject variability exists in the expression of adverse effects, as well as intra-subject variability during treatment, suggesting the development of pharmacodynamic tolerance. Thus, rational selection of an SSRI on the basis of comparative tolerability is possible, but largely empirical without further scientific evidence from clinical trials specifically designed to differentiate drugs according to their adverse effect profile.

Pharmacokinetics of the newer antidepressants: clinical relevance

The newer antidepressants are a diverse group of compounds with distinct pharmacokinetic properties. The selective serotonin reuptake inhibitors (SSRIs)--paroxetine, sertraline, and fluvoxamine--have elimination half-lives of 15-26 hours. The extended half-life of fluoxetine (4-6 days) and its active metabolite, norfluoxetine (4-16 days), results in an extended time to steady-state and a prolonged washout period when dosing is discontinued. The SSRIs are administered as a single daily dose. Venlafaxine and nefazodone have short half-lives, 2-5 hours, and are dosed > or = 2 times daily. The newer antidepressants are all highly cleared from the body through hepatic metabolism. The biotransformation of all the drugs except paroxetine and fluvoxamine results in the formation of pharmacologically active metabolites. The newer antidepressants display a broad variability similar to the tricyclic antidepressants (TCAs) in steady-state drug concentrations. Due largely to a safer toxicity profile, the variability in clearance is of lesser importance with the newer antidepressants than with the TCAs. No useable concentration versus therapeutic effect relationship has been found with the newer drugs, and widely varying concentrations appear to have little relationship to adverse effects. Knowledge of kinetic characteristics is important for designing dosage regimens and avoiding potentially serious drug-drug interactions that are mediated through inhibition of specific hepatic cytochrome P450 enzyme pathways. Each of the SSRIs inhibits at least one cytochrome P450 enzyme, and all of the SSRIs increase serum concentrations of concomitantly administered TCAs.

Prescription-event monitoring of 10,401 patients treated with fluvoxamine

Prescription-event monitoring (PEM) is one of two national systems of drug safety monitoring practised in Britain. The objective of this PEM study was to assess the safety of fluvoxamine and to monitor the occurrence of untoward and other events during treatment. A total of 10,401 patients treated with the drug in general practices throughout England were studied and data were analysed in the Drug Safety Research Unit, Southampton. The main outcome measures were the overall incidence of events per 1000 patients; the incidence during the first month of treatment; the mean incidence for months 2-6 of treatment; and the ratio of these rates as a signal that an event could be drug related. The most commonly reported category of events was neuropsychiatric while the most commonly reported individual events were nausea and vomiting. Fluvoxamine was shown to be a safe drug and no unexpected or previously undetected drug-related events were encountered. There was a relatively high incidence of gastro-intestinal symptoms, but other adverse reactions often encountered during treatment with tricyclic antidepressants were not frequently reported.