Norprolac (Quinagolide)

Quinagolide acts on the dopaminergic pathway to control prolactin excess.

• Hyperprolactinemia: normalizes serum prolactin levels, helping to restore regular menstrual cycles in women and normalize gonadal function in men.
• Prolactin‑producing pituitary adenomas: reduces tumor‑derived prolactin secretion, supporting medical management of microadenomas and adjunctive therapy for larger lesions.
• Infertility related to elevated prolactin: lowers prolactin concentrations, facilitating ovulation and improving chances of conception.
• Galactorrhea: suppresses inappropriate lactation by decreasing prolactin secretion.

• Quinagolide is a selective dopamine D2 receptor agonist. By binding to D2 receptors on lactotroph cells in the anterior pituitary, it inhibits adenylate cyclase activity, reducing cyclic AMP formation and consequently suppressing prolactin synthesis and release. The resulting decline in circulating prolactin restores normal hypothalamic‑pituitary‑gonadal axis function. This pharmacologic effect is dose‑dependent and occurs without significant stimulation of peripheral dopamine pathways, limiting motor side effects.

Quinagolide may be associated with a range of adverse reactions, varying in frequency and severity.

Common Side Effects

• Nausea: mild to moderate stomach upset that may occur after dosing.
• Headache: transient cranial discomfort, often relieved with simple analgesics.
• Dizziness: sensation of light‑headedness, particularly when rising quickly.
• Fatigue: general tiredness or reduced energy levels during daily activities.

Serious or Rare Side Effects

• Valvular heart disease: rare fibro‑proliferative changes that can affect cardiac valve function.
• Psychosis: emergence or worsening of hallucinations, delusions, or severe mood disturbances.
• Severe hypotension: marked drop in blood pressure that may cause fainting or falls.

When prescribing Quinagolide, clinicians should consider several precautionary measures to ensure safe use.

• Renal impairment: adjust monitoring as reduced clearance may increase exposure.
• Hepatic dysfunction: use caution; liver disease can alter drug metabolism.
• Cardiovascular disease: evaluate for pre‑existing valve abnormalities before initiation.
• Psychiatric history: monitor patients with schizophrenia or mood disorders for symptom exacerbation.
• Pregnancy and lactation: avoid use unless benefits outweigh potential risks, as safety data are limited.
• Store at ambient temperature: keep below 25 °C, retain in original packaging, protect from moisture and direct sunlight.

Quinagolide can interact with other medicines, influencing its efficacy or safety profile.

Major Interactions (Avoid)

• Antipsychotics (e.g., haloperidol, risperidone): dopamine antagonists may negate Quinagolide’s effect.
• Ergot derivatives (e.g., bromocriptine): combined dopaminergic activity increases risk of valvular heart disease.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): may raise Quinagolide plasma levels.
• CYP3A4 inducers (e.g., rifampicin, carbamazepine): may reduce therapeutic concentrations.
• Antihypertensives: additive blood pressure‑lowering effect, monitor for hypotension.
• Hormonal contraceptives: possible alteration of hormonal balance, observe menstrual changes.