The relevance of a First-World therapeutic drug monitoring service to the treatment of epilepsy in Third-World conditions.

In May 1988 a Therapeutic Drug Monitoring (TDM) service for anti-epileptic drugs was established at Prince Mshiyeni Memorial Hospital. This service was offered as a multidisciplinary team approach involving sisters, doctors, social workers and pharmacists at an epilepsy clinic. Statistics gathered over a 13-month period showed that: (i) epileptic patient numbers increased from 52 to 211 per 4-week cycle, while patients requiring TDM decreased from 40 to 20 per cycle; (ii) phenytoin was the most frequently prescribed anticonvulsant, followed by carbamazepine and phenobarbitone, throughout the period; (iii) TDM did not alter prescribing patterns--approximately 90% of patients were on monotherapy at the beginning and at the end of the assessment period; (iv) 471 serum levels were measured in 280 patients over 13 months. Phenytoin serum levels constituted the majority (53%) followed by carbamazepine (33%), phenobarbitone (12%) and valproate (2%); (v) of the levels measured in 24 patients taking phenytoin 300 mg/d who were experiencing neither seizures nor side-effects, 38% of levels were in the potentially toxic range; and (vi) well-controlled patients increased from 36% in the first cycle to 60% in the last cycle. A TDM service is very useful in a Third-World setting and can assist in conserving scarce sources provided it is utilised within a holistic treatment framework.