Pharmacovigilance through consumer feedback (reporting) in the mass treatment of lymphatic filariasis using diethylcarbamazine and albendazole in two districts of Sri Lanka

Objective  To document the types and severity of adverse drug reactions to diethylcarbamazine and albendazole in randomly selected urban populations from Colombo and rural populations from Gampaha, Sri Lanka.
Methods  Interviewers administered a pre-tested questionnaire to elicit information about the type and severity of adverse drug reactions experienced by recipients. Seeking medical treatment and requiring hospital admission for the adverse drug reactions were used as indicators for severity. The sample population was selected using the cluster sampling method.
Results  Two thousand three hundred and nineteen persons aged 10 to 90 years (median 40.0) responded to the questionnaire; 63.9% of them had received and ingested the drugs. 12.6% reported that they had experienced adverse drug reactions, the proportion being similar in urban and rural areas (χ² = 0.05; p = 0.82). Commonly reported reactions were drowsiness (34.7%), headache (23.1%), gastrointestinal symptoms (18.7%) and dizziness or faintness (11.9%). However, most symptoms were mild (96.3%) and did not interfere with daily activities or require medical attention. 3.2% said that they sought medical advice for their symptoms; one person (0.5%) who had severe abdominal pain was hospitalized.
Conclusions  Fewer people experienced adverse drug reactions than in previous years, possibly due to lower microfilariaemia prevalence after several rounds of mass drug administration against filariasis. Community awareness of adverse drug reactions is essential for improving compliance and for the success of the filariasis elimination programme.