Drowsiness fenfluramine

The effect of fenfluramine is usually not one of stimulation but of calmness or drowsiness. However, in predisposed subjects, it can precipitate psychotic illness. Several published cases illustrate this (267). It is wise to avoid fenfluramine in patients prone to endogenous depression or psychosis. 

Anorectic drugs act mainly on the satiety centre in the hypothalamus (1). They also have metabohc effects involving fat and carbohydrate metaboUsm. Most of them are structurally related to amfetamine and increase physical activity. Their therapeutic effect tends to abate after some months, and part of this reduction in effect may be due to chemical alterations in the brain. Fenfluramine commonly produces drowsiness in normal doses, but has stimulaut effects in overdosage. Dexamfetamine, phenmetrazine, and benzfetamine all tend to cause euphoria, with a risk of addiction. Euphoria occasionally occurs with amfepramone (diethylpropion), phentermine, and chlorphentermine, but to a much lesser extent. Some adverse effects are due to sympathetic stimulation and gastrointestinal irritation these may necessitate withdrawal but are never serious. There are interactions with monoamine oxidase inhibitors and antihypertensive drugs. 

A recent review stated that serious ADRs, such as pulmonary arterial hypertension and heart valve regurgitation/ valvular heart disease, were associated with the use of fenfluramine in patients [43 ] [32 ]. In the product information for flenfluramine, the most commonly occurring ADRs (5% of patients using this agent) were palpitations, HTN/HoTN, rash/urticarial, diarrhoea, nausea, abdominal pain, dry mouth, myalgia, drowsiness, dizziness, confusion, anxiety and abnormal dreams [44 ]. 

In contrast to many other classes of compounds, the activity of many CNS agents has been found clinically.Fenfluramine is an example of such a clinical finding. Fenfluramine (XIV) is presently marketed in 22 countries as an effective and safe anorexigenic drug. Though a phenethylamine derivative, the compound produced sedation and drowsiness in man as a side effect in the anorexigenic studies . 

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