FATAL HYPERPYREXIA WITH PHENELZINE AND IMIPRAMINE

Hyperthermia and rhabdomyolysis in self-poisoning with paracetamol and salicylates. Report of a case

A young women ingested large amounts of different analgesics, mainly salicylate and paracetamol. On admission about 17 hours later, clearly toxic serum levels of both drugs were demonstrated. She was comatose with respiratory failure for 5 days. During the first day there was a period of several hours of therapy-resistant hyperthermia. A severe bleeding tendency was probably related to profound coagulation defects. Persistingly elevated serum levels of ASAT and ALAT for two weeks were presumably caused by a toxic effect of paracetamol on the liver. When consciousness was regained, widespread pareses of skeletal muscles, predominantly of the lower limbs, were demonstrated. These were related to extensive rhabdomyolysis as evidenced by extremely elevated serums levels of CPK for 6 weeks, and by muscle necrosis in biopsy specimens. There was a gradual improvement, but walking disturbances were still present after one year. The hyperthermia was probably related to the cerebral effects of salicylates or the combination of multiple drugs. The rhabdomyolysis might be related to a deleterious effect of hyperthermia on the muscles or to an effect of paracetamol on the skeletal muscles similar to that which might occur in the myocardium, or to a combination of these mechanisms.

Serotonin syndrome: history and risk

This review focuses on the history of investigations into the behavioural reaction resulting from excess stimulation of post-synaptic 5-hydroxytryptamine receptors and the relative risk of this occurring with different combinations of drugs. Other aspects, particularly treatment with 5-hydroxytryptamine receptor antagonists, are reviewed in a recent separate paper [44]. The first human case was in 1955 and animal work had defined the characteristic features by 1958, and established they were lessened by chlorpromazine. Substantial evidence of a 'dose-effect' relationship existed by 1984. The relative risk with different drug combinations is assessed from available evidence and argued to be strongly associated with the degree of elevation of 5-hydroxytryptamine, which is greatest following combinations of irreversible inhibitors of monoamine oxidase A and B with potent serotonin reuptake inhibitors. The various serotonergic drugs that may be implicated in serotonin syndrome are tabulated and discussed in relation to the relative risk. It is suggested that the proposed 'diagnostic criteria' for serotonin syndrome are inappropriate since there is a continuous spectrum from side effects to toxicity. The term 'serotonin syndrome' may encourage the presumption that it is an idiosyncratic response, as neuroleptic malignant syndrome is usually considered to be. The terms 'toxic serotomimetic reaction' or 'toxic serotonin syndrome' may be preferable alternatives. The differences between serotonin syndrome and neuroleptic malignant syndrome are highlighted with examples from difficult or questionable cases in the recent literature. It is proposed that more systematic national collection of toxicity data is essential in order to quantify the relative risk of serotonin syndrome with various combinations of serotonergic drugs.

Fatal disseminated intravascular coagulation following a monoamine oxidase inhibitor/tricyclic interaction

In spite of intensive therapy, an otherwise fit 34-year-old man died following the hyperpyrexial reaction to an interaction between tranylcypromine and clomipramine. There was no evidence of drug overdose, but severe disseminated intravascular coagulation developed which proved fatal.

Changes in body temperature after administration of adrenergic and serotonergic agents and related drugs including antidepressants

This survey, the third in a series, presents extensive tabulations of literature, primarily since 1965, on thermoregulatory effects of adrenergic and serotonergic agonists and their antagonists including ergot alkaloids, amphetamines, tryptamines, monoamine oxidase inhibitors, tricyclic and other antidepressants, a variety of other agents which alter presynaptic aminergic mechanisms including reserpine, 6-hydroxydopamine, p-chlorophenylalanine, alpha-methyltyrosines, cocaine, guanethidine and bretylium. The information listed includes the species used, route of administration and dose of drug, the environmental temperature at which the experiments were performed, the number of tests, the direction and magnitude of body temperature change and remarks on the presence of special conditions, such as age or lesions, or on the influence of other drugs, such as antagonists, on the response to the primary drug.

Psychological effects caused by drugs in overdose

Drug overdose is a common occurrence which accounts for up to 25% of medical inpatient admissions. Intentional overdose or attempted suicide is the most common cause of overdose, but there are other types of overdose which are often unrecognised as are the effects caused by these overdoses. Iatrogenic overdose occurs frequently and is often unavoidable. Many patients will make mistakes with their treatment and unwittingly suffer from the toxic effects of the drugs they are taking. About 7% of intentional overdose patients who are admitted to hospital have taken the drug for some psychological effect they have been seeking and have taken too much. This group is described as those who take 'drugs for kicks'. As many of the drugs taken cross the blood-brain barrier and exert some toxic effect on the cerebral cortex, secondary psychological disturbances frequently occur in all of these groups of patients, and can sometimes be the only sign of dangerous toxicity. It is important to recognise the patient's gross disturbances of behaviour, thinking and perception as a manifestation of drug toxicity which can be life threatening and often requires intense medical treatment. The range of the psychological response is somewhat limited and there is not a specific psychological disturbance characteristic of the toxicity of each group of drugs. However, there are some reactions which, coupled with the physical symptoms shown by the patient, can help to identify the patient as suffering from the toxic effects of drugs and even give some indication as to the type of drugs taken. This article describes the various psychiatric syndromes caused by drugs in overdose and attempts to identify these with most of the commonly encountered groups of drugs.

Malignant hyperthermia caused by salicylate overdose associated with phenelzine therapy-a case report

A patient was admitted following a self-administered salicylate overdose. She rapidly deteriorated and died in spite of resuscitative measures. Features of her death included hyperthermia convulsions, hypoxia, acidaemia, extreme muscular rigidity, a high serum creatine phosphokinase, hypocalcaemia, hyperphosphataemia, raised potassium, and increasingly abnormal coagulation parameters. The patient had been receiving phenelzine 45 mg daily but none was detected on analysis of gastric aspirate. Her serum salicylate level was extremely high (120 mg/100 ml).

Malignant hyperthermia, its association with monoamine oxidase inhibitors, and its possible relationship in this case to salicylate overdosage with acidaemia are discussed.

A study of refractory cases of depressive illnesses and their response to combined antidepressant treatment

Opinions differ on the effectiveness and the risk involved in treating depressive illnesses with combinations of monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants. Some authorities, including the Food and Drug Administration in the United States, the former Witts Committee in this country, and the pharmaceutical firms producing antidepressants, have given serious warnings against combining MAOIs with tricyclic antidepressants. These warnings have been repeated more recently by Beck (1967), Malitz (1966) and Shepherd et al. (1968).

Dextromethorphan-monoamine oxidase inhibitor interaction in rabbits

Severe toxic reactions may occur clinically when imipramine, pethidine or dextromethorphan is administered to a patient being treated with a monoamine oxidase inhibitor (MAOI). Previous reports indicate that imipramine or pethidine produces symptoms characterized by motor restlessness, tremor, extreme hyperpyrexia and death when administered to phenelzine-pretreated rabbits. The present study shows that dextromethorphan (5 mg kg−1) produces identical symptoms in rabbits pretreated with phenelzine sulphate (30 mg kg−1) or nialamide HCl (50 mg kg−1) 42 and 18 h before temperature recording. The dextromethorphan-MAOI interaction appears to be due to a 5-hydroxytryptamine potentiation. In the unanaesthetized cat nictitating membrane preparation, dextromethorphan (5 mg kg−1) markedly enhanced the response of noradrenaline and 5-HT but antagonized the effects of tyramine. This suggests that dextromethorphan blocks the uptake of these amines in the adrenergic nerve endings.

Antihistamine-monoamine oxidase inhibitor interaction in rabbits

The ability of a drug to produce a fatal hyperpyrexia in rabbits pretreated with a monoamine oxidase inhibitor (MAOI) may be predictive of a serious clinical drug-drug interaction. These interactions appear to be due to 5-hydroxytryptamine (5-HT) potentiation. Since some antihistamines have been shown to block the neuronal 5-HT uptake, several antihistamines were tested in phenelzine-pretreated rabbits. The alkylamines (dexchlorpheniramine, chlorpheniramine, dexbrompheniramine, brompheniramine and pheniramine) and the ethylenediamines (mepyramine and tripelennamine) were active in producing a fatal hyperpyrexia in the MAOI-pretreated rabbits. Diphenhydramine and triprolidine produced a fatal hyperpyrexia in approximately one half of the animals tested. The mechanism responsible for the interaction between chlorpheniramine, a representative of the active compounds, and phenelzine appears to be 5-HT potentiation. Antihistamines that did not produce a fatal hyperpyrexia in the phenelzine pretreated rabbits were: phenyltoloxamine, promethazine, methdilazine, trimeprazine, meclizine, chlorcyclizine, cyproheptadine, phenindamine and dimethpyrindene. The potential use of the active compounds as antidepressants is also discussed.