Ethchlorvynol Pharmacokinetics During Long‐term Administration in a Patient with Hyperlipidemia and Hypothyroidism

A 33‐year‐old obese, hypothyroid, white male with several medical problems was admitted to University Hospital in September 1984 for treatment of drug intoxication. Admitting medications included ethchlorvynol in addition to other central nervous system depressants. Initial serum concentrations were reported at 70 μg/ml in this somnolent yet totally conscious adult. Established therapeutic concentrations are 2–8 μg/ml, with toxic exceeding 20 μg/ml. A tolerance phenomenon seemed evident. Serum ethchlorvynol concentrations were monitored daily during early hospitalization and continued to be substantially greater than reported toxic concentrations. Kinetic values were as follows: total body clearance 9.92 ml/min, volume of distribution 68.0 liters, and half‐life 78 hours. These values are unique in that they were calculated from a patient who had not suffered an acute overdose, thereby differing markedly from previously published values. The influence of hypothyroidism and hyperlipidemia on these markedly different values appears to be significant. Ethchlorvynol should probably be added to the list of drugs influenced by thyroid disease. 1986 Pharmacotherapy Publications Inc.