Sedation from antipsychotics

Besides weight gain, probably the most common side effect from antipsychotics in young people is sedation. Histamine receptor blockade appears to mediate this side effect. Excessive sleepiness can interfere with a youth s academic performance, cause sluggishness, and cause a child to appear drugged to their peers and family. 

Antipsychotics may increase sedation from depressant substances, e.g. opiates... 

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... 

From the pharmacological point of view antipsychotics are subdivided into two groups, the newer atypical and older typical. They work in different ways. The newer atypicals tend to have fewer side effects and are generally less sedating. 

The impact of antipsychotic agents on consciousness is immediately apparent from the frequency with which sedation and drowsiness are reported as side effects (Tune et ah, 1991), a property which historically has been used as a treat-... 

Pharmacodynamics, antipsychotics also differ in their pharmacodynamics, i.e. their pharmacological and clinical profiles of action. A rough distinction is made between highly sedative, hypnotic antipsychotics (e.g. clopenthixol, levomepromazine) and other products with weaker initial sedative action (e.g. fluphenazine and haloperidol). Sedative antipsychotics are prescribed for states of major unrest, often combined with insomnia, whereas the less sedative antipsychotics are preferred for patients suffering from delusions and hallucinations but in whom heavy sedation during daytime is undesirable. 

Antipsychotics have been used to promote sleep in resistant insomnia occurring as part of another psychiatric disorder, probably due to a combination of 5HT2-receptor, -adrenoceptor and histanaine Hj-receptor antagonism, in addition to their primary dopamine antagonist effects. Their long action leads to daytime sedation and extrap5n a-midal movement disorders may result from dopamine receptor blockade (see p. 380, Antipsychotics). Nevertheless, modern antipsychotics, e.g. quetia-pine, have been occasionally used for intractable insonmia. 

Chlorpromazine produces a tranquihty characterized by a detached serenity without depression of mental faculties or clouding of consciousness. It depresses the CNS selectively by reducing input directed to the reticular formation through collaterals arriving from the sensory pathways. Chlorpromazine-induced sedation differs from that caused by barbiturates in that the patient can be easily aroused. In practice, the more sedative neuroleptics are often prescribed for agitated, overactive patients, and the less sedative agents are used for apathetic, withdrawn patients. However, sedation is not necessary for its antipsychotic property for two reasons (1) tolerance develops to the sedative effects, and (2) fluphenazine, prochlorperazine, and trifluoperazine are excellent neuroleptics that lack pronounced sedative effects. 

In general, antipsychotics (tranquilizers) are primarily employed for the treatment of symptoms in mental diseases, their overall influenee being to free the mind from passion or disturbance and thus elam the mind i.e., they cause sedation without indueing sleep. 

---