Pharmacokinetics of the dopamine partial agonist, terguride, in the rat and rhesus monkey

3H-labelled terguride was rapidly and completely absorbed in the rat after oral administration of up to 50 mg/kg. In the rhesus monkey, absorption was prolonged. The bioavailability of terguride was 79% in the rat and 15% in the monkey. Plasma levels of the unchanged drug declined with a half-life of 50 min (rat) or 20 min (monkey). Tissue distribution as studied by autoradiography in pregnant rats showed highest concentrations of labelled compounds in the liver, the cervical gland and the kidney. Lower levels were found in the thymus, the spinal cord, the placenta and the heart muscle followed by the fetal tissue, the muscles and the brain. Radioactivity was excreted mainly in the faeces when administered to the rat and to a higher extent in the urine after treatment of rhesus monkeys.