Chlorpromazine side effects

Chlorpromazine had been shown to produce a tranquil state in animals and since it had a similar effect in humans it became known as a major tranquiliser but the term is rarely used today. Sometimes the drugs used to treat schizophrenia are called anti-psychotics but more commonly neuroleptics. Leptic means to activate (take hold of) and in animals these compounds produce a state of maintained motor tone known as catalepsy. This is an extrapyramidal effect and in schizophrenics the neuroleptics can cause a number of extrapyramidal side-effects (EPSs) including Parkinsonism. The new term neuroleptic is unsatisfactory as a description of clinically useful drugs. It really describes a condition (catalepsy) seen in animals and is more indicative of a compound s ability to produce EPSs than to treat schizophrenia. Antipsychotic is more descriptive but could imply a more general efficacy in psychoses than is the case. It would seem more appropriate to call a drug that is used to treat schizophrenia an antischizophrenic just as we use the terms antidepressant or antiepileptic irrespective of how the drug works. Despite such personal reservations, the term neuroleptic will be used in this text. 

Serious side-effects have been associated with the important psychotherapeutic agent, chlorpromazine (358), almost since its introduction. High sensitivity to sunburn, pigmentation of the skin and ocular opacity are common phototoxic effects [ 196]. In a series of phenothiazines, the chloro-substituted compounds, particularly chlorpromazine, prochlorperazine and perphenazine, showed by far the greatest phototoxic activity [197, 198]. 

These medications cannot be dosed solely based on their dopamine receptor blocking potency, because they also have effects on other receptors that must be factored into their dosing (see Table 4.6). For example, it is not unusual to begin treatment of a psychotic patient with a 5 mg dose of haloperidol. In terms of dopamine receptor blocking potency, 5 mg of haloperidol is more or less equivalent to 500 mg of chlorpromazine. If a patient were immediately treated with 500 mg of chlorpromazine, however, he/she would likely have side effect problems such as dizziness and excessive sedation. This is because the medications with the lowest dopamine receptor blocking potency are the most potent at other receptor systems responsible for these side effects. (See Table 4.7) The evolution of antipsychotics from low to medium to high potency has been driven not only by the desire to find... 

Chlorpromazine (Thorazine). The first of the modern antipsychotics, chlorproma-zine has in recent years been more widely used in Europe than the United States. In addition to treating psychosis, chlorpromazine is sometimes used to treat insomnia. Due to its overall side effect burden and potential risk of TD, we prefer not to use chlorpromazine to treat insomnia unless the patient also has a psychotic disorder. 

Drugs that are successful in treating the disease act as dopamine receptor blockers and are known as antipsychot-ics or neuroleptics (e.g. chlorpromazine, haloperidol). Antipsychotic drags reduce some of the symptoms, especially the delusions and hallucinations. A side-effect of the drugs is that they can result in symptoms similar to those seen in patients with Parkinson s disease. This is not surprising, since the hypothesis to explain Parkinson s disease is too low a concentration of dopamine in a specific area of the brain (see below). 

Largactil is a proprietary preparation of chlorpromazine, an aliphatic antipsychotic with marked sedation and moderate antimuscarinic and extrapyramidal side-effects. Serenace is a proprietary preparation of haloperidol, a butyrophenone antipsychotic with marked extrapyramidal side-effects, moderate sedation but not very likely to cause hypotension. Tegretol is a proprietary preparation of carbamazepine, an anti-epileptic drug indicated in partial and secondary generalised tonic-clonic seizures, primary generalised tonic-clonic seizures, trigeminal neuralgia and in the prophylaxis of bipolar disorder unresponsive to lithium. 

Haloperidol is a butyrophenone that is associated with a high incidence of extra pyramidal side-effects. It brings about a rapid control of agitation and restlessness and is preferred to chlorpromazine in the elderly because it causes less hypotension. 

Prochlorperazine is a potent phenothiazine antipsychotic drug that is associated with a high risk of extrapyramidal side-effects, a low degree of sedation and of antimuscarinic side-effects. Chlorpromazine is less likely to induce extrapyramidal side-effects but has increased risks of inducing sedation and antimuscarinic side-effects. Olanzapine is classified as an atypical antipsychotic having characteristically much fewer incidences of extrapyramidal... 

Although normally administered in comparatively large doses the concentration of unaltered chlorpromazine in plasma is usually too low to be measured except by sensitive GLC methods (C6, C15). Using such a technique, Curry et al. (C18) have shown that the optimum antipsychotic effect appears to occur at plasma levels which are lower than those causing side effects in chronically treated patients but higher than those causing these effects in acutely treated patients. ... 

Loxapine is a more expressed, active antipsychotic than chlorpromazine. Its sedative effect is inferior to that of chlorpromazine. Indications for its use and side effects correspond with those of phenothiazine derivatives. Loxapine is used for treating psychotic disturbances, in particular cases of chronic and severe schizophrenia. Synonyms of this drug are loxapac and loxitane. 

Chlorpromazine may cause or be associated with a variety of undesirable side effects, which are summarized in the following categories ... 

A variety of relatively uncommon dermatological side effects have been noted to be associated with antipsychotic agents. These include maculopapular rashes, urticaria, and erythema multiforme (Arana, 2000). Photosensitivity and skin pigmentation can also occur during treatment with these drugs. Although skin pigmentation has been most frequently reported with chlorpromazine, this can occur with thioridazine and trifluoperazine (Harth and Rapoport, 1996). In addition, treatment-induced alopecia has been reported for haloperidol, olanzapine, and risperidone (Mercke et ah, 2000). 

CPRG = Clinical Psychopharmacology Group rating scale for mania (R. Takahashi et ah 1975) CPZ = chlorpromazine DB = double-blind EPS = extrapyramidal side effect ... 

---