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Biomedical subjects

C C Hug

Publications and source records attributed to C C Hug.

At least 91 records · Page 5Linked to original sources
PubMed1980

Intravenous fentanyl kinetics.

Fentanyl is considered to be a short-acting narcotic analgesic but prolonged and recurrent ventilatory depression has been reported. We examined fentanyl kinetics and excretion in 7 healthy male subjects who were given a 3.2- or 6.4-micrograms/kg dose of 3H-fentanyl intravenously. Arterial blood and urine samples were analyzed for unchanged fentanyl and total radioactivity. Fentanyl concentrations fell rapidly and 98.6% of the dose was eliminated from plasma in 60 min but the terminal elimination phase of fentanyl from the body was slow (t1/2 beta = 219 min) due to the slow return of the unchanged drug from a peripheral compartment to the central compartment where elimination occurred primarily by biotransformation. Eighty-five percent of the dose was recovered in urine and feces in 72 hr; less than 8% was recovered as unchanged fentanyl. There were fluctuations in plasma fentanyl levels during the elimination phase in all cases. The long t1/2 beta and fluctuations in plasma levels may contribute to prolonged and recurrent ventilatory effects of fentanyl.

Adult↗
PubMed1979

Pharmacokinetics of 3H-fentanyl in the dog anesthetized with enflurane.

Fentanyl is often used as an anesthetic supplement for short procedures because it has a rapid onset and brief duration of action. However, persistence of ventilatory depression several hours following the last dose has been seen. The authors studied the pharmacokinetics of fentanyl in the dog to find an explanation for the occasionally prolonged duration of action. 3H-fentanyl citrate, 10 or 100 microgram/kg, was injected intravenously in dogs anesthetized with enflurane-O2. Arterial plasma and urine were analyzed for unchanged 3H-fentanyl and for total 3H radioactivity. Kinetic indices were derived by nonlinear least-squares analysis of log concentration (ng/ml) vs. time relationships. Initially, the elimination of fentanyl from plasma was very rapid, and 98 per cent of the amount administered was removed from plasma in the first 5 min after an intravenous injection. However, the terminal elimination phase was prolonged (t1/2 = 199 +/- 17 min). The apparent volume of distribution was large (9.81/kg) and independent of dose. Repetitive doses produced an accumulation of fentanyl. 3H-labelled metabolites of fentanyl were present in the earliest samples of plasma, and accounted for the major portion of the total 3H radioactivity in both plasma and urine. Urine collected for six hours contained 36 per cent of the total 3H radioactivity administered, but only 4 per cent of fentanyl administered was excreted as unchanged fentanyl. The authors conclude that most of a single dose of fentanyl is rapidly eliminated from the body by biotransformation and leads to accumulation of the drug when administered in very large or repeated doses. Under these circumstances the slow release of drug from tissues results in persistent plasma levels of fentanyl and a prolonged duration of action.

Anesthesia, Inhalation↗