Evaluation of Potential Drug-Drug Interactions among Mentally Ill Patients Admitted At Mathari Mental Hospital
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Background: Mental health refers to a wider range of activities directly or indirectly related to the mental well-being. Multiple social, psychological and biological factors determine the level of mental health of a person at any given time. Mentally ill patients are prone to a high risk of polypharmacy, complex therapeutic regimen and frequent modification of therapy. Hence an increase in the likelihood of potential drug-drug interactions, which are, estimated to account for 11% of adverse related hospital admissions. This necessitates a need to explore the overall pattern of potential drug interactions and their risk factors among mentally ill inpatients at Mathari Mental Hospital.

Objective: To evaluate potential drug-drug interactions among mentally ill patients admitted at Mathari Mental Hospital

Study Area: Mathari Mental Hospital is a national referral and teaching psychiatric hospital in Kenya, it mainly admits patients whose behavioral disturbances and mental cases cannot be managed within the community.

Study design: A retrospective descriptive cross-sectional study of medical records data of patients who had undergone mental treatment and were admitted at Mathari Mental Hospital between July and December 2013. Prescriptions were obtained by systematic random sampling method and checked using medscape drug interaction checker for any potential drug-drug interaction.

Study Population: The study comprised of all mentally ill patients who were admitted and put on medication during the study period at Mathari Mental Hospital, and were of either gender aged between 13 to 75 years.

Results: One hundred and seventy five patient files were sampled, married and unemployed patients had a statistically significant (p<0.05) association with potentially serious drug interactions. The average drugs prescribed per prescription was seven. Participants with bipolar mood disorder had a statistically significant association with potentially serious drug interactions [OR 4.39 CI (1.09, 17.46) p = 0.04]. There was a statistically significant association of potentially serious drug interactions with fluphenazine [OR 10.38 CI (4.66, 23.10) p<0.01) haloperidol [OR 4.39 CI (2.29, 8.41) p<0.01] and amitriptyline [OR 3.39 CI (1.36, 8.41) p=0.01].

Conclusion and recommendation: Married, unemployed and patients on fluphenazine, haloperidol, amitriptyline and chlorpromazine were at a higher risk of having potentially serious drug-drug interactions. These drugs exhibited both pharmacodynamic and pharmacokinetic drug interaction mechanisms. There is need to use second generation antidepressants mainly because of their improved tolerability and safety profile. We recommend continuous electrocardiogram for patients on specific antipsychotics like haloperidol