Nalbuphine

Nalbuphine is an opioid with kappa-agonistic and mu-antagonistic properties. Beside the essential agonistic (analgesic) effect nalbuphine has antagonistic effects of about a fourth of nalorfine and ten times of pentazocine.

Nalbuphine has minimal abuse potential and has no effect on the digestive and urinary smooth muscles. Nalbuphine minimally delays gastric emptying and intestinal transit. It does not induce difficulty in micturition.

In adults, the effect takes place 2 to 3 minutes after intravenous administration and less than 15 minutes after intramuscular or subcutaneous injection.

The duration of action ranges from 3 to 6 hours.The half-life period is 2,93 ± 0,795 hours.

In children of 1.5 years of age and above, the effect takes place 2 to 3 minutes after intravenous injection and 20 to 30 minutes after intramuscular or subcutaneous injection. The duration of action ranges from 3 to 4 hours.

The protein binding of nalbuphine is moderate (about 50%).

Nalbuphine hydrochloride is metabolised in the liver. There are seven metabolites that are already isolated. The most important metabolite is N-(hydroxyketocyclobutyl)-methylnornalbuphine, the other metabolites are isomers of the same and correspond to hydroxylated nalbuphine. All metabolites seem to have no particular effect.

There is no information regarding enzymes catalysing the formation of these metabolites.

Nalbuphine hydrochloride is excreted in the urine in terms of glucuronide metabolites.

No studies have been performed in patients with renal impairment or hepatic impairment.

Reproductive toxicity studies with parenterally administered nalbuphine were performed in rats and rabbits. In a pre- and postnatal study in rats, an increase in pre- and postnatal mortality and a decrease in offspring weight were observed at high doses.

Nalbuphine exerted no effects on fertility in male and female rats. No teratogenic effect was observed in rats and rabbits.