Endocrine System-Oral Antidiabetic drugs -Dopamine D2 agonist

Name of the Oral Antidiabetic drugs -Dopamine D2 agonist

1.Bromocriptine

Mechanism of Action

Inhibits release of prolactin and growth hormone from the anterior pituitary gland, thus restoring testicular or ovarian function and suppressing lactation. Bromocriptine decreases dopamine turnover in the CNS, depleting dopamine or blocking its receptors in the brain, alleviating dyskinesia

Pharmacokinetics

• Peak plasma time (Cycloset): 53 minutes (fasted); 90-120 minutes (high-fat meal)
• Bioavailability (Cycloset): 55-66%
• Protein bound (Parlodel): 90-96% (to albumin)
• Metabolism: Parlodel: Primarily hepatic via CYP3A; extensive first-pass biotransformation
• Half-life: 4.85 hr (Parlodel); 6 hr (Cycloset)
• Excretion: Feces (~82%); urine (2-6%)

Administration

• Give with meals or milk.
• If desired, give at bedtime to minimize dizziness and nausea.
• For Cycloset, administer within 2 hours of patient’s waking in the morning and with food.

Contraindications

• Hypersensitivity to drug, its components, or other ergot-related drugs
• Severe peripheral vascular disease
• Uncontrolled hypertension, syncopal migraines
• Breastfeeding

Precautions:

• Impaired hepatic or cardiac function, renal disease, hypertension, pituitary tumor
• Psychiatric disorders
• Galactose intolerance, severe lactose deficiency, glucose-galactose malabsorption (use not recommended)
• Concomitant use with anti-hypertensives
• Concomitant use with dopamine antagonists such as neuroleptic agents (use not recommended)
• Pregnant patients
• Children younger than age 15

Adverse reactions

•  CNS: asthenia, confusion, headache, dizziness, fatigue, delusions, nervousness, mania, insomnia, nightmares, seizures, cerebrovascular accident
• CV: hypotension, palpitations, extrasystoles, syncope, arrhythmias, bradycardia, acute myocardial infarction
• EENT: blurred vision, diplopia, burning sensation in eyes, amblyopia, rhinitis, sinusitis, nasal congestion
• GI: dyspepsia, nausea, vomiting, diarrhea, constipation, abdominal cramps, anorexia, dry mouth, GI hemorrhage
• GU: urinary incontinence, polyuria, urinary retention
• Musculoskeletal: leg cramps
• Skin: urticaria, coolness and pallor of fingers and toes, rash on face and arms, alopecia
• Other: metallic taste, digital vasospasm (in acromegaly use only), infection

Patient monitoring

• Monitor blood pressure to detect hypotension.
• When giving drug for hyperprolactinemia, monitor serum prolactin.
• When giving drug for acromegaly, monitor growth hormone levels to help guide dosage adjustment.
• When giving drug for diabetes mellitus, monitor blood glucose and hemoglobin A1C levels.
• In long-term use, monitor respiratory, hepatic, cardiovascular, and renal function.

Patient teaching

• Instruct patient to take Cycloset within 2 hours of waking in the morning and with food.
• Caution patient not to drink alcohol because of risk of severe reaction.
• Advise patient to have regular dental exams. Drug causes dry mouth, possibly resulting in caries and periodontal disorders.
• To minimize constipation, instruct patient to exercise regularly, increase dietary fiber intake, and drink plenty of fluids (3,000 ml daily).
• Advise patient who doesn’t desire pregnancy to use reliable contraceptive, because drug may restore fertility.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.

Nursing Considerations

• Use bromocriptine cautiously if patient has a history of psychosis or cardiovascular disease, especially after MI with residual arrhythmia. In severe psychotic disorder, bromocriptine isn’t recommended because it may worsen the disorder or reduce the effects of drugs used to treat it.
• Expect to perform a pregnancy test every 4 weeks during the amenorrheic period. Once menses resume, test whenever a period is missed, as ordered.
• Plan to withhold bromocriptine if patient becomes pregnant.
• If rapidly expanding adenoma needs continued therapy, watch closely for hypertensive crisis.
• Bromocriptine shouldn’t be given postpartum if patient has a history of coronary artery disease or other severe cardiovascular problem unless risk of withdrawing drug is greater than risk of use. If so, monitor closely for signs and symptoms of CV dysfunction, such as chest pain.
• Expect to give drug with levodopa if patient is being treated for Parkinson’s disease.
• Assess for hypotension when bromocriptine therapy starts and hypertension (typically during second week). Monitor blood pressure often if patient takes other antihypertensives.
• If patient has a history of peptic ulcer or GI bleeding, watch for new bleeding.
• Take safety precautions, such as keeping bed in low position with side rails up, because drug can cause dizziness, drowsiness, light-headedness, and syncope.

REFERENCES

1. Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
2. McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
3. April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
4. Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
5. Nursebro.com, Search – Nursebro

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