BROMOCRIPTINE MESYLATE

BROMOCRIPTINE MESYLATE (broe-moe-krip'teen) Parlodel Classifications: ergot alkaloid; antiparkinson agent; Therapeutic:ergot replacement; antidyskinetic Prototype: Ergotamine Pregnancy Category: C

Availability

2.5 mg tablets; 5 mg capsules

Action

Semisynthetic ergot alkaloid derivative, but devoid of oxytocic activity. Additionally, is a synthetic dopamine agonist. Reduces elevated serum prolactin levels in men and women by activating postsynaptic dopaminergic receptors in hypothalamus to stimulate release of prolactin-inhibiting factor and possibly luteinizing hormone release factor. Activates dopaminergic receptors in neostriatum of CNS, which may explain action in Parkinsonism.

Therapeutic Effect

Restores ovulation and ovarian function in amenorrheic women, thus correcting female infertility secondary to elevated prolactin levels. Activates dopaminergic receptors in CNS resulting in antiparkinsonism effect.

Uses

Short-term management of amenorrhea/galactorrhea or female infertility associated with hyperprolactinemia (when there is no indication of pituitary tumor). Also used as adjunctive to levodopa or levodopa/carbidopa therapy to relieve symptoms of Parkinson's disease and to lower plasma growth hormone in patients with acromegaly.

Unlabeled Uses

To prevent postpartum lactation, to relieve premenstrual symptoms, to treat hypogonadism and galactorrhea in hyperprolactinemic men; for management of hepatic encephalopathy, Cushing's syndrome, drug-induced neuroleptic malignant syndrome, and cocaine withdrawal.

Contraindications

Hypersensitivity to ergot alkaloids; uncontrolled hypertension; severe ischemic heart disease or peripheral vascular disease; pituitary tumor; normal prolactin levels, lactation, pregnancy (category C); preeclampsia, eclampsia. Safe use in children <15 y is not established.

Cautious Use

Hepatic and renal dysfunction; history of psychiatric disorder; history of GI bleeding or peptic ulcer; history of MI with residual arrhythmia.

Route & Dosage

Amenorrhea or Galactorrhea, Female Infertility Adult: PO 1.25–2.5 mg/d (max: 2.5 mg 2–3 times/d) Suppression of Postpartum Lactation Adult: PO 2.5 mg b.i.d. starting at least 4 h after delivery for 14–21 d Parkinson's Disease Adult: PO 1.25–2.5 mg/d (max: 100 mg/d in divided doses) Acromegaly Adult: PO 1.25–2.5 mg/d for 3 d, then increase by 1.25–2.5 mg q3–7d until desired effect is achieved, usually 30–60 mg/d in divided doses

Administration

Oral

• Do not begin therapy unless vital signs are stabilized.
• Give with meals, milk, or other food to reduce incidence of GI side effects.
• Have patient in supine position before receiving first dose because dizziness and fainting may occur. For this reason, initial dose is usually prescribed for evening administration.
• Note: Withhold therapy until 4 h after delivery and then begin only if vital signs have stabilized.
• Store in tightly closed, light-resistant containers, preferably at 15°–30° C (59°–86° F) unless otherwise directed.

Adverse Effects (≥1%)

Body as a Whole: Mostly dose related. CNS: Headache, dizziness, vertigo, light-headedness, fainting, sedation, nightmares, insomnia, dyskinesia, ataxia; mania, nervousness, anxiety, depression. CV: Orthostatic hypotension, shock, postpartum hypertension, palpitation, extrasystoles, Raynaud's phenomenon, red, tender, hot, edematous extremities (erythromelalgia), exacerbation of angina, arrhythmias, acute MI. Special Senses: Blurred vision, burning sensation in eyes, blepharospasm, diplopia. GI: Nausea, vomiting, abdominal cramps, epigastric pain, constipation (long-term use) or diarrhea; metallic taste, dry mouth, dysphagia, anorexia, peptic ulcers. Skin: Urticaria, rash, mottling, livedo reticularis. Other: Fatigue, nasal congestion, asthenia.

Interactions

Drug: Possibility of decreased tolerance to alcohol; antihypertensive agents add to hypotensive effects; oral contraceptives, estrogen, progestins may interfere with effect of bromocriptine by causing amenorrhea and galactorrhea; phenothiazines, tricyclic antidepressants, methyldopa, reserpine can cause an increase in prolactin, which may interfere with bromocriptine activity.

Pharmacokinetics

Absorption: 28% from GI tract. Peak: 1–2 h. Duration: 4–8 h. Metabolism: In liver by CYP3A4. Elimination: 85% in feces in 5 d; 3–6% in urine. Half-Life: 50 h.

Nursing Implications

Assessment & Drug Effects

• Monitor vital signs closely during the first few days and periodically throughout therapy.
• Lab tests: Periodic CBC, liver functions and renal functions with prolonged therapy.
• Monitor for and report psychotic symptoms and other adverse reactions in Parkinson's patients because larger doses are used.
• Improvement in Parkinson's disease may be noted in 30–90 min following administration of bromocriptine, with maximum effect in 2 h.

Patient & Family Education

• Make position changes slowly and in stages, especially from lying down to standing, and to dangle legs over bed for a few minutes before walking. Lie down immediately if light-headedness or dizziness occurs.
• Do not drive or engage in other potentially hazardous activities until response to drug is known.
• Avoid exposure to cold and report the onset of pallor of fingers or toes.
• Note: Patients taking bromocriptine to suppress postpartum lactation may have temporary rebound breast enlargement and pain following drug withdrawal.
• Note: Restoration of regular menses usually occurs in 6–8 wk. Since fertility may be restored during therapy, advise patients being treated for amenorrhea and galactorrhea to use barrier-type contraceptive measures until normal ovulating cycle is restored. Oral contraceptives are contraindicated.
• Inform physician immediately, if pregnancy occurs during therapy. Bromocriptine should be discontinued without delay.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug