Antipsychotic drugs depot

Across the sites, an average of 15% of inpatients received depot antipsychotic drugs (Sim etal, 2004b). This was most common in Singapore (75%) followed by Taiwan (20%), Japan and China (6%). The depot antipsychotic drugs used were fluphenazine decanoate, flupenthixol decanoate, zuclopenthixol decanoate, haloperidol decanoate, pipothiazine palmitate, and fluphenazine enanthate. 

Intramuscular (IM) Into skeletal muscle. This route is used to deliver depot antipsychotic drugs like fluphenazine and haloperidol decanoate, which are used in the treatment of schizophrenia. 

Depot injection A long-acting formulation of an antipsychotic drug given by occasional (often monthly) intramuscular injection. 

The 2004 Practice Guideline for the Treatment of Patients With Schizophrenia recommends indefinite maintenance treatment for patients who have had at least two episodes of psychosis within 5 years or who have had multiple previous episodes (Lehman et al. 2004). Maintenance therapy should involve the lowest possible doses of antipsychotic drugs, and patients should be monitored closely for symptoms of relapse. If the patient is compliant with treatment, oral medications are usually sufficient. However, if the patient s treatment history suggests that the patient may not reliably take daily oral medication, a long-acting depot preparation may be indicated. 

Stroke is a matter of increasing concern with some antipsychotic drugs, and the Canadian Medicine Agency has issued a warning that there is a risk of stroke with risperidone (116). On April 2005, the FDA issued an alert and asked the company to add the following information to both the oral and depot formulations The FDA has found that older patients treated with atypical neuroleptic drugs for dementia had a higher chance for death than patients who did not take the medicine. This is not an approved use (117). In some countries, the use of... 

Parenteral formulations of certain antipsychotic drugs (e.g., fluphenazine, haioperidol) are available for rapid initiation of treatment and for maintenance therapy in noncompliant patients. Depot forms of both drugs exist. 

A parenteral, depot antipsychotic is one that can be administered in such a way that, after a single dose, a therapeutically efficient tissue concentration of at least 1 week s duration is achieved (251,252). Slow release of the active drug is produced by combining the base antipsychotic with a fatty acid (decanoic acid). The alcohol group of the antipsychotic is esterified by the acid, producing a lipophilic compound whose solubility in oil is increased. An oil, usually sesame, is then used as a vehicle for intramuscular injection, where the ester, which is not pharmacologically active, is hydrolyzed by tissue esterases, slowly releasing the active compound. An alternative technique is the use of microspheres (e.g., risperidone). 

Conversely, certain forms of intramuscular antipsychotics that enter the bloodstream slowly have been developed. This method of depot administration may prove helpful if the patient has poor selfadherence to drug therapy and neglects to take his or... 

Barnes TR, Curson DA (1994) Long-term depot antipsychotics. A risk-benefit assessment. Drug Saf 10(6) 464-479... 

Zero-order absorption processes apply to iron, to depot i.m. formulations and to drug implants, e.g. antipsychotics and sex hormones. 

Examples of plasma half-lives for antipsychotics include quetiapine 7 h, clozapine 12 h, haloperidol 18 h and olazapine 33 h. Depot intramuscular injections are available from which drug is released over 2-4 weeks. 

Haloperidol was introduced for the treatment of psychoses in Europe in 1958 and in the United States in 1967 (Fig. 22.7). it is an effective aiternative to more famiiiar antipsychotic phenothiazine drugs and also is used for the manic phase of bipolar (manic-depressive) disorder. Haloperidol decanoate has been introduced as depot maintenance therapy. When injected every 4 to 6 weeks, the drug appears to be as effective as daily orally administered haloperidol. Other currently available (mostly in Europe) butyrophenones include the very potent spiperone (spiroperidol) as well as trifluperidol and droperidol. Droperidol, a short-acting, sedating butyrophenone, is used in anesthesia for its sedating and antiemetic effects and, sometimes, in psychiatric emergencies as a sedative-neuroleptic. Droperidol often is administered in combination with the potent narcotic analgesic fentanyl for preanesthetic sedation and anesthesia. 

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