Serum methadone as an aid in managing methadone maintenance patients.

Serial serum methadone levels were obtained in two patients who were experiencing significant difficulties (including subjective and objective evidence of the opiate withdrawal syndrome) while on methadone maintenance. A precipitous drop in blood levels of methadone was recorded 2 to 6 hours after ingestion. It was during this same time period that withdrawal symptoms were most severe. When methadone was administered on a divided dosage regimen, there was a dramatic clinical improvement in both patients and a marked flattening of the curve of serum methadone levels. This pilot study suggests that the current practice of administering methadone as a single daily dose to all patients needs reconsideration; serial serum methadone levels may be helpful in determining which patients do better on a divided dosage regimen.