[The effect of Ritalin, CB-154 and various drugs of serum GH in acromegalics (author's transl)].

The present study was undertaken to investigate the effects of dopaminergic agents and hypothalamic-releasing hormones on the GH release in acromegalics and normal volunteers. In the methylphenidate (Ritalin) test, nine normal volunteers and four acromegalics were examined. In other tests, five acromegalics were examined. The dopaminergic agents were administered to the subjects orally early in the morning after overnight fasting, but the hypothalamic-releasing hormones were given intravenously at the same time. The results were as follows: (1) The oral administration of 20 mg of Ritalin failed to have any effect on the GH release in normal subjects, and caused a decrease of serum GH level in only one of four acromegalics, the same case which showed an increased GH response to 1-DOPA. In the other three patients, Ritalin did not effect the GH release. Long-term administration of this drug to the acromegalics who showed depression of GH levels resulted in only slightly depressed GH levels. (2) Each oral administration of 2.5 mg of CB-154 or 500 mg of 1-DOPA caused a significant decrease of serum GH level in acromegalics, but CB-154 showed a longer and more stable suppression of serum GH level in all acromegalics. Furthermore, long-term administration of this drug resulted in a continuing inhibited serum GH level without the existence of any serious side effects. It thus seems likely that CB-154 might be a safe and effective drug for the medical treatment of acromegalics. However, while 1-DOPA also caused a significant decrease of serum GH level in four out of five acromegalics, its effect was of much shorter duration. (3) The intravenous administration of 500 microgram of TRH showed a significant increase of serum GH level in four out of five acromegalics, but LH-RH did not have any effect on GH release in any of the acromegalic cases. It seems likely from these results that dopaminergic agents, especially CB-154, may be beneficial for the medical treatment of acromegaly.