Hormonal Ergot-derived Dopamine D2 AgonistFDA-approved medicinePrescription drug

Cabergoline (Dostinex / Caber)

Dostinex

Evidence: Approved label. Example dose: finalize with a provider. Not a fact-check stamp.

0.25mg – 0.25-0.5 mg Oral 2x weekly

Prolactin InhibitorFDA-Approved (hyperprolactinemia)

Cabergoline is a long-acting ergot-derived dopamine D2 receptor agonist. It is FDA-approved under the brand name Dostinex (and internationally as Cabaser) for the treatment of hyperprolactinemia, whether idiopathic or secondary to a pituitary prolactin-secreting adenoma (prolactinoma). In Europe and some other markets it is also approved as an adjunct in Parkinson's disease at higher doses. It is strongly preferred over the older dopamine agonist bromocriptine because of its longer half-life, twice-weekly dosing schedule, and better tolerability profile.

Quick Start

Route

Oral

Start low

0.25mg Oral

Frequency

2x weekly

Timing

Take with food to reduce nausea

Take 0.25-0.5 mg twice weekly (for example Monday and Thursday) with food - empty-stomach dosing amplifies nausea. Bedtime dosing sidesteps peak nausea and dizziness by sleeping through the Tmax. Start at 0.25 mg twice weekly and only increase if prolactin remains elevated. Monitor for orthostatic hypotension, especially on first doses.

❋

Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.

Tiered Protocols · lowest first

Conservative start

0.25mg · Oral · 2x weekly

conservative starter

0.25mg

2x weekly

Expert

Prolactin Management

0.25-0.5 mg · Oral · Weekly

human clinical trial · Webster et al. 1994 (N Engl J Med)

Used aggressively by bodybuilders to prevent prolactin-induced gynecomastia from 19-Nor steroid derivatives.

0.25-0.5 mg

Weekly

◆

How it works

Cabergoline is a potent and selective agonist at dopamine D2 receptors, with much weaker activity at D1, serotonergic (5-HT2A, 5-HT2B), and adrenergic receptors. In the anterior pituitary, D2 stimulation on lactotroph cells directly suppresses prolactin synthesis and secretion - this is the basis of its approved use in hyperprolactinemia and its off-label use in controlling prolactin elevation from 19-nor anabolic steroids.

The long half-life (~63-68 hours) reflects tight binding to pituitary D2 receptors and is responsible for the clinically useful 2x/week dosing schedule. A single 0.5 mg dose suppresses prolactin for over a week in most users.

At the much higher doses used in Parkinson's disease (3+ mg/day), serotonin 5-HT2B receptor agonism on cardiac valve leaflets has been implicated in the valvulopathy cases reported with chronic high-dose use. At the sub-1 mg weekly doses used for hyperprolactinemia, cardiac valve risk has been studied extensively and appears minimal but not zero - periodic echocardiographic monitoring is reasonable with long-term use.

What to expect

Early

Days 1–7

Day 1-3: mild nausea, dizziness, possible orthostatic hypotension on the first dose. Most users acclimate within 3-5 doses.

Mid

Weeks 2–4

Week 2-4: measurable prolactin reduction. Symptomatic improvement in libido, erectile function, galactorrhea, and mood begins.

Later

Weeks 4–12

Month 1-3: full symptomatic benefit. Dose can be titrated down to the minimum effective maintenance level. For 19-nor steroid users, cabergoline is continued throughout the cycle and tapered off post-cycle.

Evidence

HumanPresent

AnimalPresent

In-vitroPresent

Each reference below was re-fetched from its PubMed record, and the quoted sentence was confirmed to appear in that abstract and to support the claim it sits under. Follow any of them to read the source.

Frequency boundary: cabergoline pharmacokinetics permit twice-weekly administration for hyperprolactinemia; this sentence does not establish the page’s exact 0.25 mg starting dose.

Mild to moderate renal and hepatic impairment, administration of food and the use of concomitant antiparkinsonian medications, such as levodopa and selegiline, have no effect on the pharmacokinetics of cabergoline.The pharmacokinetic properties of cabergoline allow once daily administration in patients with Parkinson's disease and twice weekly administration in patients with hyperprolactinaemia, making this drug advantageous over other dopaminergic agents in term of both therapeutic compliance and better symptom control.

Clinical pharmacokinetics of cabergoline. Clinical pharmacokinetics · 2003 · PMID 12844325

Evidence scope. Clinical pharmacokinetic review spanning healthy adults, Parkinson disease, and hyperprolactinemia; oral administration is described elsewhere in the same abstract, but the quoted frequency sentence does not state a dose.

Mechanism: cabergoline is a long-acting dopamine agonist that suppresses prolactin secretion in women with hyperprolactinemic amenorrhea.

Cabergoline is a long-acting dopamine-agonist drug that suppresses prolactin secretion and restores gonadal function in women with hyperprolactinemic amenorrhea.

A comparison of cabergoline and bromocriptine in the treatment of hyperprolactinemic amenorrhea. Cabergoline Comparative Study Group. The New England journal of medicine · 1994 · PMID 7915824

Evidence scope. Human randomized comparative trial in 459 women with hyperprolactinemic amenorrhea; oral cabergoline 0.5-1.0 mg twice weekly, not the page’s 0.25 mg start.

Common safety effects at studied twice-weekly doses were usually transient nausea, headache, dizziness, fatigue, and constipation.

Over 95% of reported symptoms were relatively trivial, most frequently transient nausea, headache, dizziness, fatigue and constipation.

Dose-dependent suppression of serum prolactin by cabergoline in hyperprolactinaemia: a placebo controlled, double blind, multicentre study. European Multicentre Cabergoline Dose-finding Study Group. Clinical endocrinology · 1992 · PMID 1286524

Evidence scope. Human placebo-controlled dose-finding trial in 188 hyperprolactinemic women; cabergoline 0.125-1.0 mg twice weekly for four weeks.

Valvular-risk boundary: doses sufficient to suppress hyperprolactinemia for 3-4 years were not associated with clinically significant valvular regurgitation in this small cross-sectional study.

Cabergoline at doses sufficient to suppress hyperprolactinaemia for a period of 3-4 years is not associated with an increased risk of clinically significant valvular regurgitation.

Low dose cabergoline for hyperprolactinaemia is not associated with clinically significant valvular heart disease. European journal of endocrinology · 2008 · PMID 18625690

Evidence scope. Human cross-sectional echocardiographic study; 44 cabergoline-treated hyperprolactinemia patients, mean cumulative dose 311 mg. This does not prove zero risk.

Countervailing valvular evidence: cumulative cabergoline exposure above 115 mg was associated with higher odds of regurgitation involving at least two valves compared with bromocriptine-only exposure.

Cumulative cabergoline exposure > 115 mg was associated with a higher age-sex adjusted odds of ≥2 valves with grade 2+ regurgitation (aOR 9.6, 95%CI:1.1-81.3, P = 0.04) compared to bromocriptine only.

Cardiac valvular abnormalities associated with use and cumulative exposure of cabergoline for hyperprolactinemia: the CATCH study. BMC endocrine disorders · 2020 · PMID 32075620

Evidence scope. Human cross-sectional community study in asymptomatic adults treated for hyperprolactinemia; abnormalities were described as primarily mild and confidence intervals were wide.

Claims we could not support

No abstract we checked supports these for this molecule at this route. That is not the same as saying they are false — it marks where the evidence is missing.

Exact initial dose/route: 0.25 mg orally twice weekly with food. Checked abstracts supported oral use and twice-weekly administration, but dose-finding abstracts used 0.125 mg or 0.5-1.0 mg twice weekly. None verified the exact 0.25 mg start plus food instruction.

Side effects & safety

Commonly reported

Nausea (especially first doses) - mitigated by food and bedtime dosing
Dizziness, orthostatic hypotension
Headache
Fatigue
Vivid dreams or disrupted sleep
Nasal congestion

Less common & notes

Constipation, dry mouth, depression or mood changes, impulse-control disorders (pathological gambling, hypersexuality, compulsive shopping - class effect of dopamine agonists), hallucinations (rare, more common at higher Parkinson's doses).
Chronic high-dose use (Parkinson's-range 3+ mg/day) has been associated with cardiac valve fibrosis via 5-HT2B agonism - risk is dose-dependent and minimal at hyperprolactinemia doses.
Raynaud's-like peripheral vasospasm is a rare ergot-class side effect.
Raises risk of pleural / retroperitoneal fibrosis with chronic high-dose use.

Pharmacokinetics

Illustrative plasma concentration · 11 d

Half-life

63-68 hours

~3 days

Peak · Tmax

2-3 hours

Elimination

2-3 weeks

To full washout

Bioavailability

~30-40%

Oral

Duration of action

3-4 days

Per dose - supports twice-weekly dosing for prolactin control

Clearance

Hepatic metabolism (hydrolysis), minor CYP3A4 involvement. Biliary and fecal excretion dominant; minor renal excretion.

Storage. Store at controlled room temperature (20-25°C / 68-77°F). Protect from light. Keep in original container. Shelf life typically 2-3 years from manufacture date. Keep out of reach of children - single tablet overdose can be significant in a child.

Regulatory status

Prescription-only (Rx) dopamine agonist. FDA-approved under brand name Dostinex (Pfizer / Pharmacia) in the United States for hyperprolactinemia. Also available internationally as Cabaser (higher-dose formulation for Parkinson's) and under various generic names. Prescription-only in the United States. Not a controlled substance. Not prohibited by WADA - dopamine agonists are not on the current WADA prohibited list.

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