Addiction to tranylcypromine

Antidepressant Withdrawal and Rebound Phenomena

BACKGROUND

Antidepressants are among the most commonly prescribed drugs worldwide. They are often discontinued, frequently without the knowledge of the prescribing physician. It is, therefore, important for physicians to be aware of the withdrawal and rebound phenomena that may arise, in order to prevent these phenomena, treat them when necessary, and counsel patients appropriately.

METHODS

This review is based on a comprehensive, structured literature search on antidepressant withdrawal phenomena that we carried out in the CENTRAL, PubMed (Medline), and Embase databases. We classified the relevant publications and reports by their methodological quality.

RESULTS

Out of a total of 2287 hits, there were 40 controlled trials, 38 cohort studies and retrospective analyses, and 271 case reports that met the inclusion criteria. Withdrawal manifestations are usually mild and self-limiting; common ones include dizziness, headache, sleep disturbances, and mood swings. More serious or pro- longed manifestations rarely arise. There is an increased risk with MAO inhibitors, tricyclic antidepressants, venlafaxine, and paroxetine; on the other hand, for agome- latine and fluoxetine, abrupt discontinuation seems to be unproblematic. There is also some evidence of rebound phenomena, i.e., of higher relapse rates or especially severe relapses of depression after the discontinuation of an anti- depressant.

CONCLUSION

A robust evidence base now indicates that there can be acute with- drawal phenomena when antidepressants are discontinued. Putative rebound phenomena have not been adequately studied to date. It is recommended that antidepressants should be tapered off over a period of more than four weeks.

Abuse and misuse of antidepressants

BACKGROUND

Rates of prescription drug abuse have reached epidemic proportions. Large-scale epidemiologic surveys of this under-recognized clinical problem have not included antidepressants despite their contribution to morbidity and mortality. The purpose of this review is to look specifically at the misuse of antidepressants and how this behavior may fit into the growing crisis of nonmedical use of prescription drugs.

METHODS

We conducted a comprehensive search on PubMed, Medline, and PsycINFO using the search terms "antidepressant", "abuse", "misuse", "nonmedical use", "dependence", and "addiction", as well as individual antidepressant classes (eg, "SSRI") and individual antidepressants (eg, "fluoxetine") in various combinations, to identify articles of antidepressant misuse and abuse.

RESULTS

A small but growing literature on the misuse and abuse of antidepressants consists largely of case reports. Most cases of antidepressant abuse have occurred in individuals with comorbid substance use and mood disorders. The most commonly reported motivation for abuse is to achieve a psychostimulant-like effect. Antidepressants are abused at high doses and via a variety of routes of administration (eg, intranasal, intravenous). Negative consequences vary based upon antidepressant class and pharmacology, but these have included seizures, confusion, and psychotic-like symptoms.

CONCLUSION

The majority of individuals prescribed antidepressants do not misuse the medication. However, certain classes of antidepressants do carry abuse potential. Vulnerable patient populations include those with a history of substance abuse and those in controlled environments. Warning signs include the presence of aberrant behaviors. Physicians should include antidepressants when screening for risky prescription medication use. When antidepressant misuse is detected, a thoughtful treatment plan, including referral to an addiction specialist, should be developed and implemented.

Do antidepressants have any potential to cause addiction?

Addiction/dependence is a syndrome in which the hallmark is a compulsive pattern of drug use. Most authorities do not regard antidepressants as causing addiction but this has been challenged. This debate is explored drawing on case reports and related clinical and pharmacological data. An extensive literature review identified 21 English language case reports of antidepressant addiction (DSM-IV 'substance dependence' criteria) published since 1963. Sixteen involved tranylcypromine or amineptine and may reflect their dopaminergic and stimulant properties. Subject characteristics included male sex (14/21), personality problems (10/21) and prior substance misuse (14/21). Withdrawal or discontinuation symptoms have long been recognized with antidepressants but other features of addiction such as tolerance and compulsive use are exceptionally rare. Common clinical problems are patients taking subtherapeutic dosages and prematurely stopping antidepressants. The pharmacodynamic profiles of most antidepressants and the absence of acute 'desirable' effects make addiction theoretically unlikely. It is concluded that, with the exception of tranylcypromine and amineptine, antidepressants do not have a clinically significant liability to cause addiction. Tranylcypromine and amineptine should be avoided in those with a history of substance misuse. Patients prescribed other antidepressants should be told that they are not addictive.

Abuse of monoamine oxidase inhibitors

Monoamine oxidase inhibitors, like other antidepressants, generally are considered free of risk for abuse. There is, however, some evidence that MAOIs possess dependence and abuse potential for some patients. We will review the available literature and describe three current cases. Recommendations for treatment are discussed briefly.

Current issues in monoamine oxidase inhibitor treatment

Interest in the monoamine oxidase (MAO) inhibitors has been revived over the past fifteen years since the publication of studies and reviews which argue their relative safety and efficacy in certain patient subgroups. The authors conclude that there is a continuing role for the MAO inhibitors in treating atypical depressive illness and panic disorders. Careful selection of patients to be commenced on MAO inhibitor treatment is advised. When prescribed alone or in combination with lithium there is evidence to support a usefulness for MAO inhibitors in depression resistant to the tricyclic antidepressants. Their efficacy in the depressed phase of bipolar affective disorder or in combination with the tricyclic antidepressants remains unproven. The risk of anaesthesia while a patient is receiving MAO inhibitor treatment may be less than heretofore believed. There is realistic hope of finding among the short-acting selective MAO inhibitors an effective antidepressant which is also free from tyramine related effects. With the increasing difficulties of evaluating new drugs on account of ethical and governmental constraints, it may however be some time before the preliminary hopeful findings can be substantiated in larger groups of patients.

Treatment strategy in depression. II. MAO inhibitors in depression resistant to cyclic antidepressants: two controlled crossover studies with tranylcypromine versus L-5-hydroxytryptophan and nomifensine

Antidepressants are ineffective in about 30% of the patients with major depression. Besides electroconvulsive therapy (ECT) and lithium, MAO inhibitors have been suggested as an alternative in such patients. In 2 controlled, partial crossover studies involving 47 patients with major depression who had already been treated unsuccessfully with at least 2 cyclic antidepressants, the effect of the MAO inhibitor tranylcypromine was studied. The first study was an open comparison with L-5-hydroxytryptophan (L-5HTP), the second study a double-blind comparison with nomifensine. Neither the patients treated with L-5HTP nor the patients treated with nomifensine, except one, improved. In contrast, tranylcypromine was effective in 50% of the patients. The depressions of the responders to tranylcypromine appeared to be more endogenous (according Newcastle Scale II) and of shorter duration than those of the non-responders. It is concluded that MAO inhibitors such as tranylcypromine are an effective alternative to ECT and lithium in patients with major depression who have failed to respond to cyclic antidepressants.

Paroxetine, a selective 5-hydroxytryptamine uptake inhibitor with antidepressant properties, lacks amphetamine-like stimulus properties in an operant drug discrimination bioassay in rodents

To evaluate whether the novel antidepressant paroxetine has any possible amphetamine-like actions, rats were trained to discriminate (+)-amphetamine sulphate in a standard two lever operant drug discrimination (DD) procedure using a fixed ratio 10 schedule of food reinforcement with a quantal, lever selection, index of the amphetamine stimulus. The 'training' dose of amphetamine was 1 mg kg-1, i.p. Rats trained with this dose of amphetamine (n = 15) learned the drug discrimination rapidly over 30 training sessions and discriminative performance in these animals was subsequently maintained at a high level of accuracy (90% correct) over a prolonged time. In tests in these trained animals, amphetamine itself and the antidepressant agents nomifensine and tranylcypromine all produced clear, unequivocal dose-related generalization to amphetamine with ED50s of 0.2, 0.5 and 1.6 mg kg-1 respectively (as determined by probit analyses). In tests with paroxetine hydrochloride it was established that, over the dose range 0.3 to 10 mg kg-1, no evidence was seen of generalization to the amphetamine stimulus. These data confirm earlier studies which suggested that some antidepressants may possess abuse potential because of their ability to induce amphetamine-like internal states. In contrast, paroxetine is devoid of such properties.

The risk-benefit assessment of antidepressant drugs

Antidepressant drugs in common use are reviewed in terms of their risks and benefits. A simple classification divides these into tricyclic antidepressants, monoamine oxidase inhibitors and second generation antidepressants. Risks may arise from the correct use of an antidepressant, from its incorrect or inappropriate use, or due to its failure to reverse the depression. The greatest risk is to leave the depression untreated. Risks due to adverse drug effects are generally predictable but in some cases are unexpected and have led to the withdrawal of the drug from the market. Assessing the benefits of antidepressant drugs is more difficult. Rating scales can be used in this context and the fact that the majority of antidepressant drugs have a similar degree of efficacy serves to emphasise the importance of making a risk-benefit assessment of each drug. This has been presented for the more widely used drugs. Safety in overdose is a particularly important benefit. The ideal antidepressant should specifically reverse depressive illness without toxic effects. Although no drug at present measures up to this it is clear that antidepressants should be prescribed, as their benefits outweigh their risks.