BROMOCRIPTINE MESYLATE

Chemistry - A dopamine agonist and prolactin inhibitor, bromocriptine mesylate is a semisyntheticergot alkaloid derivative. It occurs as a yellowish-white powder and is slightly soluble in water andsparingly soluble in alcohol. Bromocriptine mesylate may also be known as bromocryptine, Bromergocryptine, or 2-Bromergocryptine.

Storage, Stability, Compatibility

Tablets and capsules should be protected from light andstored in tight containers at temperatures less than 25°C.

Pharmacology - BROMOCRIPTINE MESYLATE

Bromocriptine exhibits multiple pharmacologic actions. It inhibits prolactin release from the anterior pituitary thereby reducing serum prolactin. The mechanism for this action isby a direct effect on the pituitary and/or stimulating postsynaptic dopamine receptors in thehypothalamus to cause release of prolactin-inhibitory factor. Bromocriptine also activatesdopaminergic receptors in the neostriatum of the brain.

Uses, Indications

Bromocriptine may potentially be of benefit in treating acromegaly/pituitary adenomas or pseudopregnancy in a variety of species. However, because of adverse effects, itspotential value for treating hyperadrenocorticism in dogs is low.

Pharmacokinetics - BROMOCRIPTINE MESYLATE

In humans, only about 28% of a bromocriptine dose is absorbed from the gutand due to a high first-pass effect only about 6% reaches the systemic circulation. Distributioncharacteristics are not well described, but in humans it is highly protein bound (90-96%) to serumalbumin. Bromocriptine is metabolized by the liver to inactive and non-toxic metabolites. It has abiphasic half life; the alpha phase is about 4 hours and the terminal phase is about 15 hours (Note:one source says 45-50 hours).

Contraindications, Precautions, Reproductive Safety

Bromocriptine is generally contraindicated in patients with hypertension. It should be used with caution in patients with hepatic disease as metabolism of the drug may be reduced. Usage during pregnancy is contraindicated, although documented teratogenicity has not been established. Because bromocriptine interferes with lactation, it should not be used in animals who are nursing.

Adverse Effects, Warnings

Bromocriptine may cause a plethora of adverse effects which areusually dose related and minimized with dosage reduction. Some more likely possibilities include:gastrointestinal effects (nausea, vomiting), nervous system effects (sedation, fatigue, etc.), andhypotension (particularly with the first dose, but it may persist).
Overdosage, Acute Toxicity - Overdosage may cause vomiting, severe nausea, and profoundhypotension. Standardized gut removal techniques should be employed when applicable and cardiovascular support instituted as needed.

Drug Interactions

If using bromocriptine for serum prolactin reduction: butyrophenones (e.g., haloperidol, azaperone), amitriptyline, phenothiazines, & reserpine may increase prolactinconcentrations and bromocriptine doses may need to be increased. Estrogens or progestins mayinterfere with the effects of bromocriptine. When used with other antihypertensive drugs, hypotensive effects may be additive. Although no conclusive evidence exists, use of bromocriptineand ergot alkaloids is not recommended. Some human patients receiving both have developedsevere hypertension and myocardial infarction. Use with alcohol may cause a disulfiram-typereaction.