Bromocriptine
Pharmacology. Bromocriptine mesylate is a semisynthetic derivative of the ergopeptide group of ergot alkaloids with dopaminergic agonist effects. It also has minor alpha-adrenergic antagonist properties. The dopaminergic effects account for its inhibition of prolactin secretion and its beneficial effects in the treatment of parkinsonism, acromegaly, neuroleptic malignant syndrome (NMS (See Altered Mental Status)), and cocaine craving, as well as its adverse effect profile and drug interactions. A key limitation is the inability to administer bromocriptine by the parenteral route coupled with poor bioavailability (only about 6% of an oral dose is absorbed). In addition, the onset of therapeutic effects (eg, alleviation of muscle rigidity, hypertension, and hyperthermia) in the treatment of NMS may take several hours to days.
Indications
Treatment of NMS caused by neuroleptic drugs (eg, haloperidol and other antipsychotics) or levodopa withdrawal. Note: If the patient has significant hyperthermia (eg, rectal or core temperature ≥40°C [104°F]), bromocriptine should be considered secondary and adjunctive therapy to immediate measures such as neuromuscular paralysis and aggressive external cooling. Its efficacy to treat NMS is uncertain, and there is concern it could worsen other types of hyperthermia (eg, malignant hyperthermia, heat stroke) owing to activation of dopamine and 5-HT2A receptors.
Bromocriptine has been used experimentally to alleviate craving for cocaine. However, a Cochrane database review (2003) concluded that current research does not support the use of dopamine agonists for treatment of cocaine dependence. Caution: There is one case report of a severe adverse reaction (hypertension, seizures, and blindness) when bromocriptine was used in a cocaine abuser during the postpartum period.
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