Effect of bromocriptin on the endocrine system and fetal development

SDZ CO 611: a highly potent glycated analog of somatostatin with improved oral activity

To obtain orally active octreotide (Sandostatin, SMS 201-995) analogs a new class of glycated somatostatin derivatives were synthesized by the Amadori reaction (Maillard reaction). The synthesis, chemical and biological characterization of a series of new compounds is described. These oligopeptides bind with high affinity to somatostatin receptors and retain full biological activity. Whereas generally polypeptide hormones are almost completely inactive after oral administration, we report here for the first time that these analogs show remarkably high activity by the oral route. Thus for example SDZ CO 611, the D(+)-maltose Amadori derivative of octreotide, has about 10 times higher oral effect bioavailability than octreotide while maintaining the selectivity, metabolic stability and long duration of action of the parent compound.

Bromocriptine and apomorphine stimulation of cortisol secretion in conscious dogs; evidence for a stimulatory site located outside the blood brain barrier

IV injections of the dopamine receptor agonists bromocriptine (0.1 mg/kg) and apomorphine (0.05 mg/kg) induced rapid and long-lasting increases of cortisol levels as measured by RIA in peripheral venous plasma of conscious dogs. Pretreatment with dopamine receptor antagonists which do not readily penetrate the blood brain barrier (domperidone, halopemide, sulpiride) abolished the release responses induced by the dopamine agonists. These results suggest that the dopamine receptor agonists stimulate cortisol release at a site located outside the blood brain barrier. In addition, some dopamine receptor antagonists (haloperidol, chlorpromazine, milenperone) were shown to cause a rapid and long-lasting increase of cortisol levels.

The safety of bromocriptine in long-term use: a review of the literature

This paper reviews the safety data on bromocriptine administration for 1 to 10 years at daily doses of 1.25 to 80 mg in over 1100 patients with pituitary hormone overproduction (mainly from prolactinomas and growth-hormone producing adenomas), at daily doses of 3.75 to 170 mg in over 700 patients with Parkinson's disease, and at daily doses of 2.5 to 20 mg in 28 patients with various other conditions. In addition, information is provided on the safety for mother and child of bromocriptine administered at daily doses of 2.5 to 35 mg throughout gestation (54 pregnancies) or during its later stages (39 pregnancies). The side-effects of long-term bromocriptine treatment are usually no different from those seen during short-term treatment; most of them are relatively benign, and they have been shown in virtually all patients to be reversible. Bromocriptine appears to have no harmful effect on hepatic, renal, haematologic, or cardiac functions. It is considered that a hitherto unknown, severe though rare side-effect of bromocriptine is unlikely to be reported after such long experience.

The safety of bromocriptine in hyperprolactinaemic female infertility: a literature review

The dopamine agonist bromocriptine has been widely used to facilitate pregnancy in hyperprolactinaemic women, with a success rate of 80% in relevant cases. Neither the inappropriate hyperprolactinaemia consequent upon bromocriptine withdrawal after conception nor the relative hypoprolactinaemia caused by treatment throughout gestation appears to affect adversely the course and outcome of pregnancy or the endocrine status of the fetus. No teratogenic effect of bromocriptine has been evidenced in humans, and no disturbances in the physical, psychomotor, and intellectual development of the offspring have been observed. Pituitary-tumor enlargement during closely supervised pregnancies very rarely leads to severe and irreversible complications; both the re-institution of bromocriptine treatment in the event of tumor enlargement and its preventive use throughout pregnancy have been shown to be effective measures. It is interesting, moreover, that a reduction of hyperprolactinaemia, compared with pregestational levels, may be seen after bromocriptine-facilitated pregnancies.

Pregnancy in hyperprolactinemic women

Pregnancy achieved in women who receive treatment to correct the secretory dysfunction of nontumoral HPRL or microprolactinomas requires close prenatal care, but generally its course does not vary from normal. When a macroprolactinoma is present, consequences of pregnancy are insignificant, provided the tumor has been previously treated or bromocriptine is given continuously during the pregnancy. On those rare occasions when symptoms of tumor growth appear during pregnancy, bromocriptine and dexamethasone effectively control such manifestations. Breast-feeding of the infant can be allowed, and a second pregnancy within a short term is not contraindicated. When a new pregnancy is not desired, nonhormonal contraceptive methods are advised. Patients with nontumoral HPRL and microadenomas require periodic checkups. Macroadenomas may be surgically excised, but longterm bromocriptine treatment also achieves good results and is highly recommended.

SMS 201-995: a very potent and selective octapeptide analogue of somatostatin with prolonged action

Stepwise modification of a conformationally stabilised analogue of the fragment of somatostatin which had been thought to be essential biologically active moiety has enabled us to synthesise the analogue H-(D) Phe-Cys-Phe-(D) Trp-Lys-Thr-Cys-Thr(ol) code-named SMS 201-995, which in vitro is three times more potent than the native hormone in inhibiting the secretion of growth hormone, which is highly resistant to degradation by pure enzymes and by tissue homogenates, which in vivo in rat and rhesus monkey is (depending on test system) at least 20 times more active than somatostatin, which is much longer acting, and which moreover in both species is much more selective in inhibiting the secretion of growth hormone than that of insulin. The compound is active by several routes of administration including the oral, is well tolerated both in laboratory animals and in man, and is currently undergoing preliminary clinical trial.

Spontaneous abortion incidence in the treatment of infertility

Analysis of published series indicates that, irrespective of the method of data collection, close agreement exists on empirically derived incidences of spontaneous abortion in North American populations, provided that age, previous abortion history, and gravidity are controlled. The normal incidence of clinically apparent abortion among first pregnancies in women under age 30 years is in the range 8.3% to 11.0%. A comprehensive analysis of published series on pregnancies after infertility treatment indicates that only three therapeutic methods are attended by an abortion incidence that approaches this asymptote: ovulation induction with bromocriptine in hyperprolactinemic anovulation (11.8%; n = 1,233 pregnancies); artificial insemination with donor semen for azoospermia (11.4%; n = 326 first pregnancies); and operation for endometriosis (9.3%; n = 768 pregnancies). Abortion incidences accompanying other modes of therapy are higher. Because increased abortion incidence is not generally recognized as a specific reproductive difficulty in infertile couples, as are the other two: i.e., refractory infertility despite technically adequate therapy and ectopic pregnancy, plausible physiologic mechanisms for abortions in specific categories of disease or treatment type are described and discussed in detail. Moreover, abortion incidence is proposed to be a sensitive and objective parameter with which to assess distortions in human reproductive physiology, especially when competing methods of infertility treatment have overall pregnancy outcomes that are thought to be similar.

Characterization of ergot and non-ergot serotonin antagonists by prolactin and growth hormone profiles during wakefulness and sleep

In order to further clarify the involvement of serotonin in the control of secretion of pituitary lactogens, diurnal and sleep prolactin (PRL) and growth hormone (GH) profiles were investigated in healthy subjects treated with ergot and non-ergot serotonin antagonists. A group of 10 subjects received a single oral dose of 2 mg each of pizotifen, methysergide, and the dopaminergic drug bromocriptine as reference substance, in comparison with placebo. Blood was collected at hourly intervals for 6 h. Another group of 10 individuals received either a placebo, 2.5 mg bromocriptine (n = 6) twice daily for 4 days or pizotifen (n = 10) 0.5 mg 3 times daily for 12 days before undergoing EEG recording and blood sampling during night sleep. The diurnal plasma profiles of PRL and GH were not modified by pizotifen, a non-ergot drug. Methysergide and bromocriptine, two ergot derivatives, significantly (P < 0.01 and P < 0.001 respectively) suppressed the basal secretion of PRL throughout the trial and increased plasma GH significantly (P < 0.01). The sleep profile of PRL was not modified by pizotifen but there was a moderate reduction in GH reaching the level of significance (P < 0.02) between hours 1 and 2 of sleep. Bromocriptine suppressed completely PRL secretion throughout the entire sleep period and significantly (P < 0.05) prolonged the secretory profile of GH. The results indicate the presence in the ergot molecule of a dopaminergic moiety responsible for PRL inhibition and GH stimulation. This effect is independent of the serotonin active component of the drug.

Effect of guanfacine on pituitary hormones in man

1 Animal studies have shown that adrenaline and noradrenaline are involved in the control of pituitary function. As very few data on this topic were available in man, some studies were carried out mainly in young normal volunteers using guanfacine, a new drug with central α-adrenoceptor properties.

2 Single oral doses of guanfacine 1 or 2 mg increased GH secretion. After 90-180 min, this increase was significant for the 2 mg dose. No effect on prolactin, ACTH, FSH and LH plasma levels was recorded. Four days of treatment with guanfacine showed:

(a) no additional stimulation of GH released by insulin;

(b) no effect on resting levels of prolactin and on prolactin released by metoclopramide, but a significant decrease of prolactin released by insulin;

(c) a statistically significant (P < 0.01) but biologically unimportant increase in LH secretion (Δ = 1.58mg/ml);

(d) a non-significant decrease of ACTH released by metyrapone (an 11-β-hydroxylase inhibitor) but a significant (P < 0.01) decrease in ACTH released by stress (insulin- induced hypoglycaemia).

3 A 7-d treatment period with guanfacine (3 mg daily) showed that the drug did not have a sustained stimulatory effect on GH and LH secretion in man.

4 These data on hormonal balance support the assumption that, in man, the central α-adrenergic system exerts a stimulatory control on GH secretion and that an adrenergic pathway, hypothalamic or extrahypothalamic, may be involved in the inhibitory control of prolactin and ACTH release induced by stress.

Chronic dopamine receptor stimulation using bromocriptine: failure to modify thyroid function

Administration of 2.5 mg bromocriptine (Parlodel), a dopamine agonist, on two occasions to six normal volunteers did not alter the plasma TSH response to an i.v. injection of 100 micrograms TRH, but significantly (P less than 0.01) blunted it after 200 micrograms. Chronic bromocriptine treatment (7.5--50 mg/day) of fifteen acromegalic subjects failed to influence basal plasma TSH or the response pattern to 200 micrograms TRH. The thyroxine Binding Index (TBI) and the levels of T3 and T4 were not modified by treatment. These results indicate that chronic dopaminergic therapy with bromocriptine does not alter thyroid function.

Intrauterine development, feto-placental function and pregnancy outcome after induction of ovulation with bromoergocryptine

18 pregnancies occurred after treatment with bromoergocryptine in 17 patients who wished to conceive, but who suffered from anovulation of varying aetiology. The course of 15 pregnancies was uneventful. Three pregnancies ended in abortion. Nine of the 17 women had hyperprolactinemic amenorrhea. Furthermore, one woman had normoprolactinemic post-pill amenorrhea, another normoprolactinemic anovulatory oligomenorrhea and a third normoprolactinemic anovulatory regular menstruations. With the exception of one woman, all had galactorrhea. The courses of pregnancy were monitored by frequent ultrasound measurements of the fetal biparietal diameter, maternal urinary estriol excretion and radioimmunological measurements of plasma estrone, estradiol, unconjugated and immunoreactive estriol, progesterone, and HPL. All data were within the normal ranges and all babies were healthy at birth and had no teratogenic defects. The data prove the great value of bromoergocryptine in the treatment of hyperprolactinemic anovulation, sometimes even in the treatment of normoprolactinemic anovulation. Moreover, the results indicate no adverse effect on either the course or the outcome of pregnancy.

New evidence for growth hormone modulation by the alpha-adrenergic system in man

The effect of BS 100-141, N-amidino 2-(2.6 dichlorophenyl) acetamide hydrochloride, a new drug with central alpha-adrenoceptor activity, on growth hormone (GH) secretion was investigated in 24 young, healthy volunteers. Six normal volunteers were treated with 1 mg and 8 with 2 mg BS 100-141; 8 of these 14 were treated with placebo, using single oral doses. Ten normal volunteers received single oral doses of 2 and 4 mg BS 100-141, 0.15 and 0.30 mg clonidine in a randomized, crossover study. GH secretion was significantly increased after 2 and 4 mg BS 100-141 and 0.30 mg clonidine. Prolactin and insulin plasma levels, glycerol, and blood sugar were not significantly influenced by BS 100-141. The results give new evidence for an alpha-adrenoceptor mechanism modulating GH secretion in normal young men.