Effect of various neuroactive drugs on bromocriptine concentration in the striatum of rats.

Parkinsonian patients are usually given several drugs concomitantly with bromocriptine, with variable results. The possibility of interference of these drugs with the availability of bromocriptine in the brain was investigated by measuring bromocriptine concentrations in the striatum in rats. After a single injection, bromocriptine concentration in the striatum was 13.1 +/- 2.9 ng/mg protein. Naloxone, an opiate receptor blocker, was found to produce the largest increase in bromocriptine content (21.7 +/- 2.5 ng/mg protein). Amantadine, diazepam and haloperidol produced the largest decreases (3.2 +/- 0.9, 3.3 +/- 0.8 and 4.4 +/- 1.2 ng/mg protein, respectively). Rats given L-dopa or benzodiazepine also showed slightly lower levels of bromocriptine.