Chemistry - A dopamine agonist and prolactin inhibitor, bromocriptine mesylate is a semisynthetic ergot alkaloid derivative. It occurs as a yellowish-white powder and is slightly soluble in water and sparingly soluble in alcohol. Bromocriptine mesylate may also be known as bromocryptine , Brom-ergocryptine , or 2-Bromergocryptine .
Storage/Stability/Compatibility - Tablets and capsules should be protected from light and stored in tight containers at temperatures less than 25°C.
Pharmacology - Bromocriptine exhibits multiple pharmacologic actions. It inhibits prolactin release from the anterior pituitary thereby reducing serum prolactin. The mechanism for this action is by a direct effect on the pituitary and/or stimulating postsynaptic dopamine receptors in the hypothalamus to cause release of prolactin-inhibitory factor. Bromocriptine also activates dopaminergic 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, its potential value for treating hyperadrenocorticism in dogs is low.
Pharmacokinetics - In humans, only about 28% of a bromocriptine dose is absorbed from the gut and due to a high first-pass effect only about 6% reaches the systemic circulation. Distribution characteristics are not well described, but in humans it is highly protein bound (90-96%) to serum albumin. Bromocriptine is metabolized by the liver to inactive and non-toxic metabolites. It has a biphasic 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 are usually dose related and minimized with dosage reduction. Some more likely possibilities include: gastrointestinal effects (nausea, vomiting), nervous system effects (sedation, fatigue, etc.), and hypotension (particularly with the first dose, but it may persist).
Overdosage/Acute Toxicity - Overdosage may cause vomiting, severe nausea, and profound hypotension. 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 prolactin concentrations and bromocriptine doses may need to be increased. Estrogens or progestins may interfere with the effects of bromocriptine. When used with other antihypertensive drugs, hypotensive effects may be additive. Although no conclusive evidence exists, use of bromocriptine and ergot alkaloids is not recommended. Some human patients receiving both have developed severe hypertension and myocardial infarction. Use with alcohol may cause a disulfiram-type reaction.
For treatment of pituitary adenoma:
a) 5 mg IM q12h. To prepare an injectable formulation for IM use from oral dosage forms: Bromocriptine mesylate 70 mg is added to 7 ml of a solution of 80% normal saline and 20% absolute alcohol (v/v). Final concentration is 1% (10 mg/ml). (Beck 1992)
Monitoring Parameters - Monitoring is dependent upon the reason for use to evaluate efficacy. However, blood pressures should be evaluated if patients have symptoms associated with hypotension.
Client Information - Have client administer drug with food to reduce GI adverse effects.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times -
Veterinary-Approved Products: None
Bromocriptine mesylate 5 mg (of bromocriptine) Capsules; Parlodel ® (Sandoz); Rx
Bromocriptine mesylate 2.5 mg (of bromocriptine) Tablets; Parlodel® Snaptabs (Sandoz); Rx
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