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"Adverse Drug
Event of the month"
Medication errors detected by Therapeutic drug monitoring We wish to highlight this month, our experiences with medication errors as seen in our Therapeutic Drug Monitoring clinic. Case 1: A 28 year old patient with generalised tonic-clonic seizures on prophylaxis with phenytoin sodium presented with a bottle containing trihexyphenidyl an anti cholinergic instead of phenytoin sodium. The error was made by the pharmacist and occurred because the bottles containing phenytoin and trihexyphenidyl looked identical, came from the same manufacturer and were stored next to each other. The patient realized that the drug dispensed was not phenytoin because the size of the tablets was different. Case2: A 40 year old male patient with Bipolar I disorder on carbamazepine (CBZ) presented with complaints of diplopia, insomnia and irritability. The levels of CBZ were found to be 17.41ug/ml, well above the therapeutic range. On close history taking, it was found that the patient was taking CBZ from two different manufacturers; Tegrital from Novartis Pharma and Zen retard from Intas Pharmaceuticals. Tegrital was prescribed by the neurologist and Zen retard was given by his general practitioner. He was instructed to discontinue Zen Retard and his subsequent blood level of CBZ done 2 weeks later was 8.41 ug/ml, well within the therapeutic range. He also improved symptomatically. Case 3: A 16-year-old male patient presented with symptoms and signs of phenytoin toxicity and was found to have toxic phenytoin levels of 26.27 ug/ml and subtherapeutic levels of phenobarbitone of 8.9 ug/ml. On history taking, it was found that the patient was taking both Eptoin (Phenytoin 100mg from Abbott India) and Epilan (Phenytoin 100 mg+ phenobarbitone 30mg from Anglo French pharmaceuticals), the first being prescribed the neurologist and the second by a general practitioner. The patient was weaned off Epilan and improved subsequently. Case 4: A 28-year-old male patient was being treated with a combination of phenobarbitone and phenytoin was found to have toxic levels of phenytoin (40.2ug/ml) during a routine follow up visit. He was found to have been prescribed twice the daily dose of phenytoin by the pharmacist, who gave him phenytoin tablets instead of phenobarbitone, since the two drugs were kept close to each other in the pharmacy. The medication errors seen by us resulted from inadequate history taking on part of the physician , the patient not revealing medication details either due to fear of offending the physician or ignorance and a dispensing error on part of the pharmacist . Worldwide poor handwriting, look alike and sound alike medications have been attributed to causing medication errors. The medication errors seen by us resulted from inadequate history taking on part of the physician, patients not giving medication details either due to fear of offending the physician or lack of knowledge and finally, dispensing errors on part of the pharmacist. Given the scenario of numerous medications available today, the responsibility of patient safety is a joint one- between the regulators, the pharmaceutical industry, the healthcare professionals and the patients themselves. This in turn can result from effective communication between the players involved. A more comprehensive list of similar sounding brand names in India in alphabetical order is available on www.kem.edu/dept/clinical_pharmacology/drug_names.htm. |