A one year-review of anti-epileptic drug monitoring in Trinidad

OBJECTIVE: To audit anti-epileptic drug monitoring in tertiary hospitals in Trinidad. METHODS: Epileptic patients, from hospital clinics, who were receiving maintenance therapy and were referred for plasma drug level monitoring, gave informed consent and were enrolled. Blood collection was at trough levels of drug and coded plasma samples were analysed by competitive immunoassay on the TDx Monitoring system. RESULTS: All 93 patients consented to participate. Phenytoin and carbamazepine were the two major drugs prescribed. The use of multiple drugs did not influence the occurrence of seizures in the patients; (31 percent) receiving polytherapy. Phenobarbital was the most frequent agent added to the drug regime in 24/9 patients (83 percent). Low plasma levels of drugs were detected in 58 percent and 36 percent of patients receiving polytherapy with phenytoin and carbamazepine respectively; but an association was not found between the range of drug levels and the frequency of seizures. Seventy-seven (83 percent) patients reported good compliance. Plasma drug levels were significantly below normal (p=0.004) in patients who reported poor compliance. CONCLUSIONS: Multiple drug therapy did not influence the prognosis of seizure control in this study. Suspected non-compliance, drug toxicity and failure to individualize dosing are considerations for plasma level drug monitoring in the protocol for management of epilepsy.(Au)

Considerations for implementing an antibiotic policy in hospital practice

An antibiotic policy should aim for the safe, effective and economical use of antimicrobial drugs, and to prevent their indiscriminate use and development of resistant bacterial strains. The term 'antibiotic' is used as a general term for all antimicrobial drugs. Antibiotics prescriptions should be based on clinical evidence of bacterial infection, preferably substantiated by appropriate laboratory culture and sensitivity tests. Viral infections are not an indication for antibiotic prescriptions. Patient factors to be considered for choice and dose of an antibiotic are age, pregnancy, lactation, renal and hepatic impairment. Immunodeficient patients should receive only bactericidal drugs. Severity of infection determines the route of administration. Duration of therapy should not exceed five days, unless specifically prescribed by the physician. An antibiotic should, if started as an empirical therapy not be changed before a minimum of three days trial. Prescriptions of drugs such as aztreonam, imipenem, vancomycin, piperacillin and amphotericin are to be restricted due to cost and toxicity and should be reviewed by the microbiologist (AU)

Therapeutic drug monitoring in the Caribbean - abstract

For many drugs there is a close relationship between plasma concentration and biological/therapeutic effects. Laboratory services for estimating plasma drug concentrations (Therapeutic Drug Monitoring or TDM) are now provided in most major hospitals of the developing world, including most of the Caribbean, for three major reasons: 1) the variable but generally long lag period in the transfer of new technology, 2) the perceived cost of the new technology, 3) the dearth of clinical pharmacologists, the specialists most closely involved in the provision and interpretation of plasma drug levels. A TDM service was set up in Barbados in 1982, in the Clinical Pharmacology Laboratory at the Queen Elizabeth Hospital using the Syva Enzyme Mediated Immuno Assay/spectophotometric system. Eight drugs are now routinely assayed, using (since January 1987) a flourescence polarisation immuno assay (Abbott), which permits rapid estimation and a same day service, facilitating immediate feedback of emergency and out-patient results. Drugs assayed include the top four anti-epileptics (phenytoin, phenobarbitone, carbamazepine and valproate), two cardiac drugs (digoxin and quinidine), theophylline and gentamycin. Assay services (including pharmacokinetic interpretation and advice on dose regimes) are provided for hospital in-and out-patients, private and polyclinic patients and, on request, to other Caribbean countries, i.e. countries of the Organisation of Eastern Caribbean States (OECS) and occasionally Jamaica. In Trinidad TDM services are provided for anti-epileptics at the Port-of-Spain General Hospital. Review of anti-epileptic TDM in Barbados indicates that drug management is usually far less than optimal. Because of its saturation kinetics, phenytoin is particularly difficult to achieve correct therapeutic levels and good results with, only 25 percent of assays falling in the recommended therapeutic range. Improved patient compliance and doctor education both require the concerted attention of the health services if the present poor epilepsy management is to be improved. TDM is less costly than perceived if the service: 1) uses a system where equipment is provided by the Company, with a contract for purchase of a minimal number of kits, rather than purchase of equipment, at high capital costs, and having to pay for service; 2) is centralised, providing large runs and minimising cost of controls, etc. Current costs per test for anti-epileptics to our lab (e.g. carbamazepine US$3.50) are comparable with basic cost to QEH of hormone assays (e.g. prolactin US$2.50, testosterone US$3.50, cortisol US$2.30). These costs are, however, multiplied by about four for private patients, or six or more by the commercial labs, where routine assays, e.g. amylase and blood count costs US$6.00 and $15.00 respectively. Since most other lab test costing must include capital equipment and service costs, the comparisons become even more favourable. Finally, assay costs are negligible compared to annual Drug costs for all relevant drugs except phenobarbitone. A select number of drug assays provide invaluable guidance in treating difficult patients with drugs which have a narrow therapeutic/toxic ratio. Anti-epileptic assays in particular are increasingly recognised to be as valuable in treating epilepsy as blood sugars in treating diabetics. No major hospital in the Caribbean or elsewhere should be without a Clinical Pharmacologist or a TDM service, providing assays for anti-epileptics, gentamycin and digoxin at least (AU)