Bromocriptine

Drug Class & Mechanism

• Pituitary: Activates dopamine receptors on lactotroph cells → suppresses prolactin (PRL) secretion
• CNS (basal ganglia): Mimics dopaminergic activity → used in Parkinson's disease
• Hypothalamus/circadian axis: Modulates central dopaminergic tone → improves glycemic control (Cycloset formulation)

Clinical Indications

Dosing

Hyperprolactinemia / Prolactinoma

• Start: 0.625–1.25 mg at bedtime with a snack (to minimize GI/orthostatic side effects)
• Titrate gradually upward
• Maintenance: Most patients controlled at ≤7.5 mg/day (typical: 2.5 mg three times daily)
• Short-acting → preferred when pregnancy is desired (can be stopped promptly once pregnancy is confirmed)

Parkinson's Disease

• Start low (1.25 mg twice daily), titrate over weeks
• Usual range: 10–40 mg/day in divided doses

Type 2 Diabetes (Cycloset)

• 0.8 mg tablets taken within 2 hours of waking
• Titrate weekly up to 1.6–4.8 mg/day
• Primarily lowers postprandial glucose with low hypoglycemia risk

Adverse Effects

Common

• Nausea, vomiting (most common — mitigated by taking with food, starting at low dose)
• Orthostatic hypotension, dizziness
• Headache
• Nasal congestion

CNS/Neuropsychiatric

• Hallucinations, confusion (especially at high doses used for Parkinson's)
• Impulse control disorders (gambling, hypersexuality — class effect of dopamine agonists)
• Somnolence, sudden sleep attacks

Serious / Rare

• Ergot-related vasospasm (Raynaud's phenomenon, digital ischemia)
• Pleuropulmonary fibrosis and retroperitoneal fibrosis (with chronic high-dose use)
• Cardiac valvulopathy (less than cabergoline, but possible)
• Stroke/seizure — reported postpartum with high doses (avoid in postpartum hypertension)

Contraindications

• Uncontrolled hypertension
• Hypersensitivity to ergot alkaloids
• Syncopal migraine
• Postpartum period (if hypertension, eclampsia, or seizures present)
• Breastfeeding (suppresses lactation — intentional or not)

Bromocriptine vs. Cabergoline

Key Points

• Bromocriptine is the preferred dopamine agonist when fertility is desired, due to its short action and extensive pregnancy safety data.
• In prolactinomas, it both normalizes PRL levels and reduces tumor size.
• The Cycloset formulation for T2DM works via a distinct central mechanism and does not cause hypoglycemia as monotherapy.
• Always start low and titrate slowly to minimize nausea and orthostatic hypotension.

Central Fever — Quick Overview

• Traumatic brain injury (TBI)
• Subarachnoid hemorrhage (SAH)
• Intracranial hemorrhage / stroke
• Hypothalamic tumors or surgery
• Severe hypoxic-ischemic encephalopathy

Role of Bromocriptine

• Hypothalamic thermoregulation is partly modulated by dopaminergic pathways
• In central fever (and in conditions like Paroxysmal Sympathetic Hyperactivity / sympathetic storming after TBI), there is dysregulated autonomic/hypothalamic activity
• Bromocriptine, as a D2 agonist, dampens hypothalamic hyperactivity and reduces sympathetic outflow → lowers temperature

1. Paroxysmal Sympathetic Hyperactivity (PSH) after TBI/SAH

• PSH causes episodic fever, tachycardia, hypertension, diaphoresis, posturing
• Bromocriptine 2.5–7.5 mg/day (in divided doses) is a recognized agent in the PSH management bundle alongside propranolol, opioids, and clonidine

2. Neuroleptic Malignant Syndrome (NMS)

• NMS is essentially central dopamine blockade → hyperthermia + rigidity
• Bromocriptine 2.5–10 mg TID directly reverses the dopamine deficit, making it one of the primary pharmacological treatments

Practical Use in Central Fever

Limitations

• Not a first-line agent for central fever in general — cooling blankets and acetaminophen are tried first
• Evidence is largely from case series and small studies, not RCTs
• Not effective if the fever has an infectious or inflammatory cause — always rule out infection before attributing fever to a central origin
• Cabergoline is sometimes preferred in NMS due to better tolerability, but bromocriptine has more established use