Bromocriptine

Chemical Properties

Crystals.

Originator

Parlodel,Sandoz,UK,1975

Uses

Enzyme inhibitor (prolactin).

Uses

Bromocriptine, a dopaminomimetic that is a dopamine D2 receptor agonist, possesses expressed antiparkinsonian activity. It is used for treating all phases of idiopathic and postencephalic Parkinsonism.

Definition

An semisynthetic ergotamine alkaloid derivative and powerful dopamine D2 agonist. It inhibits prolactin secretion and release from the pituitary and retards tumor growth.

Manufacturing Process

A solution of 3.4 grams of N-bromosuccinimide in 60 cc of absolute dioxane is added drop wise in the dark, during the course of 5 minutes, to a stirred solution, heated to 60°C, of 9.2 grams of ergocryptine in 180 cc of absolute dioxane. The reaction mixture is stirred at this temperature for 70 minutes and is concentrated to a syrup-like consistency in a rotary evaporator at a bath temperature of 50°C. The reaction mixture is subsequently diluted with 300 cc of methylene chloride, is covered with a layer of about 200 cc of a 2 N sodium carbonate solution in a separating funnel and is shaken thoroughly. The aqueous phase is extracted thrice with 100 cc amounts of methylene chloride. The combined organic phases are washed once with 50 cc of water, are dried over sodium sulfate and the solvent is removed under a vacuum.
The resulting brown foam is chromatographed on a 50-fold quantity of aluminum oxide of activity II-III with 0.2% ethanol in methylene chloride as eluant, whereby the compound indicated in the heading is eluted immediately after a secondary fraction which migrates somewhat more rapidly than the fractions containing the heading compound. The last fractions to leave the aluminum oxide contain varying amounts of starting material together with the heading compound, and may be subjected directly, as mixed fractions, to an afterbromination in accordance with the method described above. The fractions containing the pure heading compound are combined and crystallized from methyl ethyl ketonehopropy1 ether. Melting point 215°-218°C (decomp.), [α]D 20-195° (c = 1 in methylene chloride).

brand name

Parlodel (Novartis);Bromed;Lactismine;Parilac;Umprel.

Therapeutic Function

Prolactin inhibitor

World Health Organization (WHO)

Bromocriptine, a semisynthetic ergot alkaloid derivative and prolactin inhibitor was introduced into medicine in 1976. It is used in the prevention of lactation, but because of the risk of rebound effect and since only 10% of women benefit therapeutically from such intervention, the United States Food and Drug Administration has requested manufacturers to no longer indicate preparations containing bromocriptine for this purpose. The World Health Organization is not aware of similar action having been taken elsewhere.

Hazard

Poison; teratogen; developmental abnor- malities of the respiratory system,musculoskeletal system, rogenital system, craniofacial area, and body wall; teratogen; mutagen; questionable car- cinogen; tumorigen; causes nausea, vomiting, orthostatic hypotension; constipation, dyskinesias, psychoses, digital spasm, erythromelalgia.

Mechanism of action

Bromocriptine is absorbed after oral administration, but approximately 90% of a dose undergoes extensive first-pass hepatic metabolism, with the remainder hydrolyzed in the liver to inactive metabolites that are eliminated mostly in the bile. The half-life is relatively short (~3 hours).

Clinical Use

Bromocriptine is an ergot peptide derivative that is a partial agonist at D1-type and a full agonist at D2-type postsynaptic dopamine receptors, usually given in combination with levodopa therapy. It was the first direct dopamine receptor agonist used in treatment of Parkinson's disease after its development as an inhibitor of prolactin release (via activation of anterior pituitary D2 receptors). At low doses (typically 1–5 mg/day), bromocriptine is an effective prolactin inhibitor, and at higher doses (typically 10–20 mg/day), the antiparkinsonism and mood-elevating effects of bromocriptine become apparent.

Side effects

Bromocriptine has a number of undesirable side effects, even causing mental disturbances in long-term use.

Synthesis

Bromocriptine, 2-bromoergocriptine (10.1.13), is a semisynthetic derivative of a natural ergot alkaloid, ergocriptin (a derivative of lysergic acid), which is synthesized by bromination of ergocriptin using N-bromosuccinimide [18,19].

Drug interactions

Potentially hazardous interactions with other drugs
Increased risk of toxicity with bromocriptine and isometheptene.

Metabolism

Bromocriptine is extensively metabolised. It undergoes extensive first-pass biotransformation in the liver, reflected by complex metabolite profiles and by almost complete absence of parent drug in urine and faeces. In plasma the elimination half life is 3-4 hours for the parent drug and 50 hours for the inactive metabolites.The parent drug and its metabolites are also completely excreted via the liver with only 6% being eliminated via the kidney.