Parlodel 2.5 mg Tablets

Brand Name

The medication is marketed under the brand name Parlodel, a well-recognized label in the field of endocrine and neurological disorder management.

International Nonproprietary Name (INN)

The active ingredient in this product is identified globally as bromocriptine, a name standardized for consistency across international pharmacological practices.

Form of Release

Parlodel is available as oral tablets and capsules. Tablets come in strengths of 2.5 mg and 5 mg, while capsules are typically 5 mg, packaged in blister packs or bottles to suit various dosing needs.

Composition

Each tablet or capsule of Parlodel contains bromocriptine mesylate as the primary active substance, with dosages of 2.5 mg or 5 mg (equivalent to bromocriptine base). The formulation includes several inactive ingredients, such as lactose monohydrate, which acts as a filler, and microcrystalline cellulose, providing structural support. Additional excipients like magnesium stearate serve as lubricants, while colloidal anhydrous silica enhances flow during manufacturing. The capsule shell may contain gelatin and titanium dioxide, with trace stabilizers ensuring the drug’s potency and shelf-life stability.

Pharmacologic Properties

Pharmacodynamics

Parlodel functions as a dopamine receptor agonist, primarily targeting D2 receptors in the pituitary gland and central nervous system. By mimicking dopamine’s inhibitory effects, it suppresses prolactin secretion from lactotroph cells, reducing elevated prolactin levels in conditions like hyperprolactinemia. This action also normalizes gonadal function by restoring gonadotropin release, aiding fertility in affected patients. In Parkinson’s disease, its stimulation of dopamine receptors in the nigrostriatal pathway compensates for dopamine deficiency, improving motor symptoms like rigidity and bradykinesia.

The medication exhibits partial D1 receptor activity and mild alpha-adrenergic antagonism, contributing to its cardiovascular effects, such as blood pressure reduction. Clinical studies show it lowers prolactin within hours and sustains motor improvement in Parkinson’s over weeks with consistent use. Its broad receptor affinity also influences growth hormone secretion in acromegaly, though less potently than prolactin suppression. This multifaceted mechanism supports its diverse therapeutic applications in hormonal and neurological contexts.

Pharmacokinetics

Following oral administration, Parlodel is absorbed from the gastrointestinal tract, with peak plasma concentrations reached within 1 to 3 hours. Bioavailability is low, around 28%, due to extensive first-pass metabolism, enhanced slightly by food intake. The drug binds to plasma proteins at approximately 90–96%, distributing widely to tissues, including the brain, pituitary, and liver.

Metabolism occurs primarily in the liver via cytochrome P450 enzyme CYP3A4, converting bromocriptine into multiple inactive metabolites. The half-life ranges from 4 to 4.5 hours for the parent compound, though its effects persist longer due to receptor binding, with a terminal elimination phase of 50–70 hours. Elimination is predominantly biliary, with over 95% excreted in feces as metabolites, and less than 6% appearing in urine, reflecting minimal renal clearance.

Indications for Use

Parlodel is prescribed for hyperprolactinemia-associated disorders, such as prolactinomas, where it reduces tumor size and normalizes prolactin levels, alleviating symptoms like galactorrhea and infertility. It is also indicated for Parkinson’s disease, improving motor function as monotherapy or adjunctive therapy with levodopa. The medication treats acromegaly by suppressing growth hormone secretion, reducing associated symptoms like soft tissue swelling.

Other uses include prevention of postpartum lactation in women not breastfeeding, where it inhibits prolactin surge, and management of menstrual irregularities or amenorrhea tied to prolactin excess. In some cases, it addresses neuroleptic malignant syndrome off-label, leveraging its dopamine agonism. These applications highlight its versatility in managing endocrine and neurological conditions effectively.

Contraindications

Parlodel is contraindicated in patients with uncontrolled hypertension, as its hypotensive effects could exacerbate cardiovascular instability. It is also prohibited in those with a history of hypersensitivity to bromocriptine, ergot alkaloids, or formulation components like lactose, where reactions may range from rash to anaphylaxis.

Severe ischemic heart disease, peripheral vascular disease, or a history of psychosis preclude its use, given risks of vasoconstriction or psychiatric exacerbation. Postpartum women with a history of coronary artery disease or severe preeclampsia should avoid it due to rare but serious cardiovascular events. Use with potent CYP3A4 inhibitors or ergot derivatives is restricted, as is administration in untreated pheochromocytoma, which could worsen catecholamine effects.

Method of Administration and Dosage

Administration Guidelines

The tablets or capsules should be taken orally, swallowed whole with water, ideally with food to reduce nausea and enhance absorption. Timing with meals or a light snack improves tolerability, especially during initial dosing. Splitting or crushing is not recommended unless directed, as it may alter release and increase side effects.

Dosage for Adults and Children

For adults with hyperprolactinemia, the typical starting dose of Parlodel is 1.25 mg to 2.5 mg daily, increased gradually by 2.5 mg every 2–7 days to 2.5–15 mg daily, divided into 2–3 doses. Parkinson’s disease begins at 1.25 mg daily, titrated weekly to 10–40 mg daily in divided doses. Acromegaly uses 1.25 mg to 2.5 mg daily, up to 20–30 mg daily as tolerated. Postpartum lactation suppression requires 2.5 mg twice daily for 14–21 days. Children under 15 are not typically prescribed this therapy, with rare exceptions for prolactinomas at adjusted doses (e.g., 1.25 mg daily).

Dose Adjustment in Specific Conditions

No specific adjustment is needed for renal impairment, as excretion is primarily biliary. Mild to moderate liver dysfunction requires caution and possible dose reduction, while severe impairment may contraindicate use due to metabolism reliance. Elderly patients or those with hypotension may start at 1.25 mg daily, with slow titration. Gradual escalation minimizes side effects, guided by clinical response and tolerance.

Side Effects

Parlodel may cause various side effects, though many patients adjust with gradual dosing. Common reactions include nausea, vomiting, or dizziness, often occurring early and subsiding with food co-administration. Headache, fatigue, or nasal congestion are also reported, typically mild and transient.

Less frequent effects include orthostatic hypotension, drowsiness, or mild hallucinations, reflecting its dopaminergic action. Rare but serious issues, such as pulmonary fibrosis, retroperitoneal fibrosis, or psychotic episodes, require immediate cessation and medical evaluation, particularly with prolonged high-dose use. Gastrointestinal upset or leg cramps may occur in some cases. Monitoring during initiation helps manage these effects and ensures safe continuation.

Overdose

Symptoms of Overdose

Excessive intake of Parlodel may amplify typical side effects, including severe nausea, hypotension, confusion, or hallucinations, with rare reports of tachycardia or lethargy. Doses exceeding 75 mg daily have shown no consistent acute toxicity pattern, but symptoms reflect exaggerated dopamine agonism.

First Aid Measures

In case of overdose, medical consultation is advised, with activated charcoal considered within 1 hour to limit absorption. Treatment focuses on supportive care, such as fluids for hypotension or rest for neurological symptoms. Monitoring blood pressure and mental status is key until recovery, typically within 24–48 hours, given the drug’s half-life.

Drug Interactions

Effects on Other Medications

Parlodel is metabolized by CYP3A4, so inhibitors like erythromycin or ketoconazole may increase levels, risking toxicity, while inducers like rifampin reduce efficacy. It may antagonize dopamine blockers (e.g., antipsychotics), decreasing their effect, or enhance hypotensive drugs, amplifying blood pressure drops. Co-use with ergot derivatives or other dopamine agonists heightens vasoconstriction risk.

It does not significantly alter cytochrome P450 substrates like warfarin but may increase levodopa effects in Parkinson’s patients. Patients should report all medications to their healthcare provider to manage these interactions, especially in complex regimens.

Compatibility with Alcohol and Food

Moderate alcohol use may worsen hypotension or drowsiness, suggesting limited intake during therapy. Food enhances absorption and tolerability, making it a recommended co-administration strategy, particularly during initial dosing to reduce nausea.

Special Precautions

Use During Pregnancy and Breastfeeding

Parlodel is Category B in pregnancy, with no clear fetal harm in limited data, used cautiously for prolactinomas if benefits outweigh risks. It suppresses lactation, so breastfeeding is not feasible during therapy, and alternative feeding is advised post-treatment until prolactin normalizes.

Women of childbearing age should use contraception during therapy unless fertility restoration is the goal, with pregnancy testing before starting in non-fertility cases.

Impact on Driving and Operating Machinery

The medication may cause drowsiness or sudden hypotensive episodes, suggesting caution with driving or machinery until tolerance is clear. Most patients adjust after initial weeks, but early use warrants avoiding such activities if affected.

Considerations for Elderly and Pediatric Populations

Elderly patients tolerate Parlodel well at lower doses, with monitoring for hypotension or confusion critical due to age-related sensitivity. Children over 15 with prolactinomas may use adult dosing, while those under 15 lack established safety data, limiting use to adolescents or adults.