Antipsychotic drugs dosages

Extrapyramidal effects usually diminish with a reduction in the dosage of the antipsychotic drug. The primary health care provider may also prescribe an antiparkinsonism drug, such as benztropine (see Chap. 29) to reduce the incidence of Parkinson-like symptoms. 

Dosages in older adults are usually in the lower range. Because older adults are more susceptible to cardiovascular and neuromuscular reactions to the antipsychotic drugs the nurse must dosely monitor them. It is important to increase the dosages gradually. 

When administering the antipsychotic drugs, the nurse observes the patient for extrapyramidal effects , which include muscular spasms of the face and neck, the inability to steep or s t still, tremors rigidity, or involuntary rhythmic movements The nurse notifiesthe primary health care provider of the occurrence of these symptoms because they may indicate a need for dosage adjustment. 

The antipsychotic drugs may cause extreme drowsinessand sedation, especially during the first or second weeks of therapy. This reaction may impair mental of physical abilities Dro wsness usually diminishesafter 2-3 weeks of therapy. However, if the patient continuesto be troubled by drowsiness and sedation, the physician may prescribe a lower dosage. 

Table 12.2 Percentages of daily dosages of antipsychotic drugs (mg chlorpromazine ...

The dosages of antipsychotic drugs differed markedly between the six sites studied (see Table 12.2). Of note, there were more than 50% of patients in China, Hong Kong, Taiwan, and Singapore taking less than 600 mg chlorpromazine-equivalents... 

Thirty-five to eighty-seven percent of the patients studied received antiparkinson drugs. Compared to other countries, Japan and Singapore used the most of these antidotes for drug-induced extrapyramidal symptoms. This is most likely related to the frequent use of high-dosage antipsychotic drugs and poly-antipsychotics (see Table 12.3). 

As with antidepressant therapy, reversal of psychosis is often gradual and may occur over several weeks to several months. Guidelines for the acute use of antipsychotic drugs are summarized in Table 4— 2 usual dosages for each of the commonly used antipsychotic drugs are summarized in Table 4—1. 

Ericksen SE, Hunt SW, Davis JM. Dosage of antipsychotic drugs [Letter]. N EnglJ Med 1979 294 1296-1297. 

Some dosage relationships between various antipsychotic drugs, as well as possible therapeutic ranges, are shown in Table 29-4. 

Olanzapine had significantly positive diabetic effects, based on both duration of treatment and dosage. All patients had been exposed to antipsychotic drugs for more than 60 days because there was less awareness of the diabetic effects of atypical antipsychotic drugs during that period, the use of these data reduced the possibility of selection bias. 

Roman M, Kronstrand R, Lindstedt D, Josefsson M (2008) Quantitation of seven low-dosage antipsychotic drugs in human postmortem blood using lc-ms-ms. J Anal Toxicol 32(2) 147—155... 

Q5 Lithium (lithium carbonate or citrate) is administered in doses of between 0.2 and 1.5 g daily. The dose is monitored to provide a therapeutic plasma level of 0. 4-1.0 mmol l-1 12 hours after the most recent dose taken on days 4-7 of treatment. The plasma concentration is then measured every week until the dosage has been stabilized and the required concentration has remained constant for four weeks. Lithium can take several days to become effective. If a patient is suffering an acute attack of mania and is excessively disturbed, treatment with an antipsychotic drug may also be required. The antipsychotic... 

Akathisia has been reported in 16% of patients taking olanzapine (SEDA-21, 56). Three patients developed severe akathisia during treatment with olanzapine (20-25 mg/day) (87). In two, the akathisia resolved after withdrawal of olanzapine and in one of those olanzapine was well tolerated when reintroduced in combination with lorazepam. In the third patient, the akathisia was controlled by dosage reduction. A 33-year-old man with AIDS and a prior history of extrapyramidal symptoms with both typical antipsychotic drugs and risperidone developed dose-dependent akathisia with olanzapine 15-19 mg/day the akathisia responded to dosage reduction and beta-blockade (88). 

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