Pharmacokinetics of a long-acting bromocriptine preparation (Parlodel LA) and its effect on release of prolactin and growth hormone

The pharmacokinetics and endocrine actions of a long-acting form of bromocriptine (Parlodel) were examined in a controlled study in 10 healthy volunteers receiving a single i.m. injection of 50 mg. Six further subjects took bromocriptine 1.25 mg t.i.d. for 3 days p.o. In the subjects given the slow...

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Bibliographic Details
Published in:European journal of clinical pharmacology 1986-01, Vol.29 (5), p.615-618
Main Authors: DEL POZO, E, SCHLÜTER, K, NÜESCH, E, ROSENTHALER, J, KERP, L
Format: Article
Language:English
Subjects:
Adult
Biological and medical sciences
Bromocriptine - administration & dosage
Bromocriptine - metabolism
Bromocriptine - pharmacology
Delayed-Action Preparations
Growth Hormone - metabolism
Hormones. Endocrine system
Humans
Kinetics
Male
Medical sciences
Pharmacology. Drug treatments
Prolactin - metabolism
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Summary:The pharmacokinetics and endocrine actions of a long-acting form of bromocriptine (Parlodel) were examined in a controlled study in 10 healthy volunteers receiving a single i.m. injection of 50 mg. Six further subjects took bromocriptine 1.25 mg t.i.d. for 3 days p.o. In the subjects given the slow release preparation, the plasma bromocriptine concentrations increased sharply to a maximum of 1.65 mg/l 2 h after injection. This fast release process was followed by slow clearance with a half-life of 16 days. The substance was still detectable in plasma 35 days postinjection. Plasma prolactin (PRL) fell rapidly from a mean of 5.6 ng/ml to reach significantly lower levels at 60 and 120 min. Inhibition was maintained for up to 35 days, when plasma PRL was still significantly below the values recorded at baseline and in the control group. Plasma GH peaked at 3.6 ng/ml at 120 min and subsequently declined slowly to stabilize between 1.4 and 2.2 ng/ml for about 12 h, falling to below the 1 ng/ml limit for the remainder of the study period. In contrast, individuals receiving oral bromocriptine exhibited a significant elevation following the first dose and an equivalent increment after the morning dose on Day 3. Thus, the results show a prolonged inhibitory effect on PRL of this long-acting bromocriptine preparation in parallel with its slow plasma clearance. The stimulant effect on GH secretion is short lived, presumably due to desensitisation of specific receptors.
ISSN:0031-6970
1432-1041
DOI:10.1007/BF00635902