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Thursday, May 5, 2011

Decision-making in the choice of a psychotropic drug

Decision-making in the choice of a psychotropic drug
Despite the considerable advances that have been made in psychopharmacological research, there are many areas in which objective decisions based on scientific evidence with regard to the choice of the appropriate drug are sparse. In an attempt to overcome this problem, several authors have recently produced prescribing guidelines based on the evidence of the most appropriate drug to use. Such evidence extends from studies that are supported by randomized control trials (highest category), those which are supported by limited controlled trials (alternative category if drugs of the first category are ineffective) to those based on uncontrolled or anecdotal evidence (lowest category, unproven usefulness). A summary of the treatment options for the major psychiatric disorders and for Alzheimer’s disease is found at the end of the appropriate chapter. General principles of prescribing psychotropic drugs

The decision to use a psychotropic drug must take into account the potential risks and benefits. This should be discussed with the patient and/ or carer. Before prescribing, a full evaluation of the symptoms should be made and the diagnosis confirmed. Polypharmacy should be avoided. If a drug combination is necessary, the pharmacodynamic and pharmacokinetic interactions should be considered. In general, the lowest effective dose of the drug should be used, particularly in elderly patients. Dose titration should be undertaken slowly. Similarly, on discontinuation of a drug, the dose should be reduced slowly, the rate of decrease being decided by the elimination half-life of the drug. Some psychotropic drugs produce a discontinuation syndrome that can usually be avoided by slow withdrawal. In particular, sedatives, anxiolytics and antidepressants can cause withdrawal effects. In switching drugs, the half-life of elimination that is being stopped should be considered if drug interactions are to be avoided. The time taken for the withdrawal of a drug depends on the duration of treatment; sedatives, antiepileptics and anxiolytics may take several weeks to withdraw.

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