BRICANYL Solution for injection or infusion Ref.[7931] Active ingredients: Terbutaline

Basic parameters have been evaluated in man after i.v. and oral administration of therapeutic doses, e.g.

i.v. single dose:

Volume of distribution (VSS): 114 L

Total body clearance (CL): 213 ml/min

Mean residence time (MRT): 9.0 h

Renal clearance (CLR): 149 ml/min (males)

Oral dose:

Renal clearance (CLR): 1.925 ml/min (males)

Renal clearance (CLR): 2.32 ml/min (females)

The plasma concentration/time curve after i.v. administration is characterised by a fast distribution phase, an intermediate elimination phase and a late elimination phase.

Terminal half-life (t_½) has been determined after single and multiple dosing (mean values varied between 16-20 h).

Bioavailability

Food reduces bioavailability following oral dosing (10% on average); fasting values of 14-15% have been obtained.

Metabolism

The main metabolite after oral dosing is the sulfate conjugate and also some glucuronide conjugate can be found in the urine.

The major toxic effect of terbutaline, observed in toxicological studies in rats and dogs at exposures in excess of maximum human exposure, is focal myocardial necrosis. This type of cardiotoxicity is a well known pharmacological manifestation seen after the administration of high doses of beta₂-agonists.

In rats, an increase in the incidence of benign uterine leiomyomas has been observed. This effect is looked upon as a class-effect observed in rodents after long term exposure to high doses of beta₂-agonists.