Bromocriptine is a dopamine agonist medication used to treat conditions associated with excessive prolactin levels and certain neurological and metabolic disorders. It works by stimulating dopamine receptors in the brain, which helps regulate hormone secretion and nerve signaling. Bromocriptine has been used in the management of hyperprolactinemia, Parkinson’s disease, and some menstrual disorders, as well as in specific cases of type 2 diabetes. When used under medical supervision, it can be effective, though possible side effects include nausea, dizziness, and low blood pressure, particularly at the start of treatment.
BRAND NAMES
Common brand names of Bromocriptine include Parlodel, Cycloset, and Bromergon. These brands are used for treating conditions like Parkinson's disease and hyperprolactinemia, depending on the formulation and dosage.
MECHANISM OF ACTION
Bromocriptine acts as a dopamine (D2) receptor agonist, stimulating dopamine receptors in the brain. This suppresses prolactin release from the pituitary gland and helps restore dopamine activity, improving symptoms in conditions like Parkinson's disease.
PHARMACOKINETICS
Absorption
Bromocriptine is well absorbed after oral administration, but its bioavailability is low (about 6–10%) due to extensive first-pass metabolism in the liver. Peak plasma concentrations are usually reached within 1–3 hours after ingestion. Food may help improve its absorption and reduce gastrointestinal side effects.
Distribution
Bromocriptine is widely distributed in the body after absorption. It is highly protein-bound (about 90–96%) in plasma and can cross the blood-brain barrier, which is essential for its action in the central nervous system. The drug also distributes to tissues like the liver, kidneys, and pituitary gland.
Metabolism
Bromocriptine is extensively metabolized in the liver, primarily by the cytochrome P450 enzyme CYP3A4. Its metabolism produces inactive metabolites, which are then excreted mainly via the bile into the feces, with only a small amount eliminated in the urine.
Excretion
Bromocriptine is primarily excreted through the bile into the feces, with only a small portion eliminated in the urine. Its elimination half-life ranges from 3 to 4 hours, though effects can persist longer due to tissue binding.
PHARMACODYNAMICS
Bromocriptine works by stimulating dopamine D2 receptors, reducing prolactin secretion and improving motor symptoms in Parkinson's disease. It also has minor effects on blood vessels through adrenergic and serotonergic receptors.
ADMINISTRATION
Bromocriptine is administered orally in the form of tablets. The dosage and frequency depend on the condition being treated, and it is usually taken with food to reduce gastrointestinal side effects.
DOSAGE AND STRENGTH
Hyperprolactinemia: Typically starts at 1.25–2.5 mg once daily, gradually increasing as needed.
Parkinson’s disease: Usually starts at 1.25 mg 1–3 times daily, with gradual titration to an effective dose (often up to 30–40 mg/day, divided doses).
Type 2 diabetes (Cycloset): Usually 0.8–1.6 mg daily in the morning, titrated as tolerated.
FOOD INTERACTIONS
High-fat meals may delay absorptionbut do not significantly reduce overall bioavailability.
Taking bromocriptine with food can help reduce nausea and gastrointestinal discomfort, which are common side effects.
Grapefruit and grapefruit juice should be avoided as they may inhibit CYP3A4, potentially increasing drug levels and side effects
DRUG INTERACTIONS
Dopamine antagonists (e.g., antipsychotics like haloperidol) can reduce its effectiveness.
CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) may increase bromocriptine levels, raising the risk of side effects.
CYP3A4 inducers (e.g., rifampin, carbamazepine) may decrease its effectiveness.
Antihypertensive drugs can enhance hypotensive effects, leading to dizziness or fainting.
CONTRAINDICATIONS
Uncontrolled hypertension or severe cardiovascular disease
History of hypersensitivity to bromocriptine or ergot derivatives
Pregnancy and breastfeeding, unless clearly needed and prescribed by a doctor
Recent heart attack (myocardial infarction)
SIDE EFFECTS
Nausea, vomiting
Headache, dizziness
Fatigue, drowsiness
Constipation
Low blood pressure (hypotension)
OVERDOSE
Severe nausea and vomiting
Low blood pressure (hypotension) and dizziness
Confusion, hallucinations, or agitation
Heart rhythm disturbances or chest pain
Severe headache
TOXICITY
Bromocriptine toxicity usually occurs with excessive doses or interactions that raise its levels. It can cause severe nausea, vomiting, low blood pressure, dizziness, confusion, hallucinations, and heart rhythm disturbances. Treatment is mainly supportive, focusing on stabilizing vital signs and managing symptoms.
