What is the recommended dose of mirtazapine (Remeron) for an 87-year-old male with impaired renal function?

From the Guidelines

For an 87-year-old male with impaired renal function, the recommended dose of mirtazapine (Remeron) should be considered carefully, with a suggested starting dose of 7.5 mg once daily at bedtime, which can be gradually increased to 15 mg daily if needed and tolerated, as indicated in the context of decreased drug clearance and increased sensitivity to medications in elderly patients and those with renal impairment 1.

When considering the dose of mirtazapine for this patient, several factors must be taken into account, including the patient's age, renal function, and potential for increased sensitivity to the medication's side effects.

• The patient's age and impaired renal function suggest the need for a lower starting dose due to decreased drug clearance and increased risk of side effects such as sedation, dizziness, and orthostatic hypotension.
• According to the study published in the American Family Physician in 2015 1, mirtazapine's dosage range is 15 to 45 mg per day for outpatients, but it is recommended to consider decreasing the dose in patients with renal or hepatic disease.
• Given the potential for increased sensitivity and side effects, it is crucial to start with a lower dose and gradually increase as needed and tolerated, with careful monitoring for side effects.
• The medication's longer half-life in elderly patients and those with kidney dysfunction further supports the need for cautious dose adjustment, typically at intervals of 1-2 weeks, while closely monitoring for efficacy and adverse effects.
• Regular assessment of renal function and medication response is essential for optimal management, and administering the medication 1-2 hours before bedtime may help minimize morning drowsiness, a common side effect.

From the FDA Drug Label

In general, dose selection for an elderly patient should be conservative, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. The clearance of mirtazapine is reduced in patients with moderate to severe renal or hepatic impairment. Consequently, plasma mirtazapine levels may be increased in these patient groups, compared to levels observed in patients without renal or hepatic impairment Dosage decrease may be necessary when administering mirtazapine tablets to patients with moderate to severe renal or hepatic impairment

The recommended dose of mirtazapine for an 87-year-old male with impaired renal function should be conservative, starting at the low end of the dosing range. A dosage decrease may be necessary due to the patient's impaired renal function. The exact dose is not specified, but it should be lower than the standard dose, considering the patient's age and renal impairment 2, 2. Key considerations include:

• Decreased clearance of mirtazapine in the elderly
• Increased risk of adverse effects in patients with renal impairment
• Need for conservative dose selection and potential dosage decrease

From the Research

Mirtazapine Dosing in Elderly Patients with Impaired Renal Function

The recommended dose of mirtazapine for an 87-year-old male with impaired renal function should be carefully considered due to the potential for reduced clearance of the drug.

• According to the study 3, liver and moderate renal impairment can cause an approximately 30% decrease in oral mirtazapine clearance, while severe renal impairment can cause a 50% decrease in clearance.
• The study 4 recommends careful dosage titration and regular monitoring for adverse events in patients with hepatic or renal insufficiency.
• The study 5 suggests starting mirtazapine therapy at a lower dose (<15 mg/d) in frail, elderly patients with underlying chronic conditions.

Dosage Recommendations

• The recommended starting dosage of mirtazapine is 15 mg/day, which may need to be adjusted based on the patient's response and tolerance 4, 6.
• In patients with impaired renal function, a lower starting dose may be necessary to avoid adverse effects.
• The dosage should be titrated carefully, and the patient should be monitored regularly for signs of adverse effects, such as somnolence, increased appetite, weight gain, and dizziness 6.

Special Considerations

• Elderly patients may be more susceptible to the adverse effects of mirtazapine, such as somnolence and dizziness, due to age-related changes in pharmacokinetics and pharmacodynamics 5.
• The patient's renal function should be monitored regularly, and the dosage of mirtazapine should be adjusted accordingly to avoid accumulation of the drug and its metabolites 3.