A CROSS-OVER STUDY WITH THE 2 NOVEL DOPAMINERGIC DRUGS CABERGOLINE AND QUINAGOLIDE IN HYPERPROLACTINEMIC PATIENTS

Cabergoline and quinagolide, two new dopamine agonist drugs with long-lasting activity, are currently under investigation for the treatment of hyperprolactinemia. At present, studies comparing these drugs for tolerability and efficacy in the same patients are lacking. It was our aim to make such a comparison in an open randomized cross-over trial. Cabergoline (0.5 mg twice weekly) and quinagolide (75 mu g once daily) were given orally. Each drug was administered for 12 weeks. Treatment with the second drug was started after the recurrence of hyperprolactinemia. Twelve women with hyperprolactinemia due to idiopathic disease (n=6), microprolactinoma (n=5) or postsurgical empty sella (n=1) were evaluated. Six women were amenorrheic and 6 were oligomenorrheic. Ten had spontaneous or provoked galactorrhea. Baseline characteristics (age, clinical signs and PRL levels) of patients initially allocated to the two treatment groups were similar. Nine patients completed both treatment cycles and PRL levels were lower under cabergoline (10.7+/-3.7 mu g/L) than under quinagolide (25.0+/-7.7 mu g/L; p<0.05). One patient discontinued cabergoline because of dryness of the eyes after having completed the quinagolide cycle and 2 patients initially treated with cabergoline discontinued quinagolide because of gastrointestinal symptoms. After completion of the first treatment cycle, the time of recurrence of hyperprolactinemia was significantly longer after cabergoline (14+/-7 weeks) than after quinagolide (5+/-1 weeks; p<0.05). At week 12, normal PRL levels (<20 mu g/L) were observed in 10 and 6 women during cabergoline and quinagolide, respectively. Only one case was resistant to both drugs. The clinical effects of the two treatments were similar. At week 12, minor side effects were described in 5 and 9 women on cabergoline and quinagolide. The number of patients without side effects was significantly higher after cabergoline (n=6) than after quinagolide (n=1; p<0.01). Our study indicates that, at the doses employed, cabergoline shows a better long-lasting efficacy and tolerability than quinagolide. Drop-outs due to severe side effects occurred with both drugs. However, quinagolide could be regarded as a further choice in the medical management of hyperprolactinemia.