Haloperidol side effects

TABLE 34-4. Comparative Side Effects among the Second-Generation Antipsychotics and Haloperidol... 

Side Effect Clozapine Risperidone Olanzapine Quetiapine Ziprasidone Aripiprazole Haloperidol... 

Some first-generation agents, such as haloperidol, are rather specific for one subtype of dopamine receptor, D2. This suggests that some degree of both efficacy and side effects are associated with dopamine antagonism at this receptor. However, the situation is complex, as usual. There are five classes of dopamine receptors known Di through D5. To complicate matters further, several of these classes have subclasses. In total, there are at least 15 dopamine receptors. Which of these is important for relief of the symptoms of schizophrenia Which is responsible for movement disorders The answers to these questions are incomplete. We do have a few hints. 

Side effects can also occur quickly after a single dose of a medication. For example, some antidepressants (e.g., selective serotonin reuptake inhibitors) can cause nausea, stomach upset, loose stools, and even diarrhea. Likewise, some anti-psychotics (e.g., haloperidol (Haldol)) can cause unpleasant or painful muscle spasms called dystonias. All of these side effects can occur within minutes or hours of taking a single dose of the medication. These side effects are also a result of the direct effects of the medication in the synapse. 

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... 

Typical Antipsychotics. Low doses of high potency typical antipsychotics such as haloperidol or fluphenazine (0.5-2mg given once or twice daily) are generally quite effective for psychotic symptoms after TBI. Unfortunately, as noted earlier, many post-TBl patients are susceptible to the extrapyramidal side effects of these medicines, especially if there was any injury to brain regions such as the basal ganglia. Low potency antipsychotics are not a viable alternative, because their anticholinergic and sedative effects are equally, if not more, problematic for patients who have suffered TBI. We recommend using typical antipsychotics, even for psychotic symptoms, as briefly as possible and in the lowest effective dose, if at all. Fortunately, there are now alternatives. 

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. 

In terms of pharmacological action, pimozide is similar to haloperidol. It is used in hospitals as well as in outpatient settings for supportive therapy of patients suffering from schizophrenia, paranoid conditions, and mental and neurotic disorders with paranoid characteristics. It is unfit for use in severe psychoses because it does not possess psychomotor-sedative action. It is used for treating patients who suffer from Turretts s syndrome. Pimozide has a number of side effects, many of which are similar to those of phe-nothiazine and a number of others. A synonym of this drug is orap. 

Like the benzodiazepines, buspirone appears to be safe even when given in very high doses. The most common side effects are dizziness, light-headedness, and headache. Abuse, dependence, and withdrawal have not been reported, and buspirone administration does not produce any cross-tolerance to the benzodiazepines. Buspirone has been reported to increase blood pressure in patients taking monoamine oxidase inhibitors, and it may increase plasma levels of haloperidol if coadministered with that agent. 

---