What is the appropriate medication dose for a 26-year-old male weighing 35.9 kg?

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Last updated: November 15, 2025View editorial policy

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Medication Dosing for 26-Year-Old Male, 35.9 kg

I cannot provide specific medication doses without knowing which medication you are asking about. However, I can provide weight-based dosing guidance for the medications discussed in the available evidence.

Tuberculosis Medications (if applicable)

For a patient weighing 35.9 kg, tuberculosis medication doses would be calculated as follows:

First-Line TB Medications - Daily Dosing 1

  • Isoniazid (INH): 5 mg/kg = 180 mg daily (maximum 300 mg) 1
  • Rifampin (RIF): 10 mg/kg = 360 mg daily (maximum 600 mg) 1
  • Pyrazinamide (PZA): For weight <40 kg, use 1,000 mg daily (18.2-25.0 mg/kg range) 1
  • Ethambutol (EMB): 15-20 mg/kg = 540-720 mg daily (maximum 1,000 mg) 1

Intermittent TB Dosing (if using twice-weekly regimen) 1

  • Isoniazid: 15 mg/kg = 540 mg twice weekly (maximum 900 mg) 1
  • Rifampin: 10 mg/kg = 360 mg twice weekly (maximum 600 mg) 1
  • Pyrazinamide: For weight <40 kg, use 2,000 mg twice weekly (36.4-50.0 mg/kg range) 1
  • Ethambutol: 50 mg/kg = 1,800 mg twice weekly (maximum 4,000 mg) 1

Weight Management Medications (if applicable)

Qsymia (Phentermine/Topiramate ER) 2

The dosing schedule is fixed and not weight-based:

  • Initial dose: 3.75 mg phentermine/23 mg topiramate daily for 14 days 2
  • Standard dose: 7.5 mg phentermine/46 mg topiramate daily after initial period 2
  • Titration dose: 11.25 mg phentermine/69 mg topiramate daily if needed 2
  • Maximum dose: 15 mg phentermine/92 mg topiramate daily 2

This patient's low weight (35.9 kg) requires special consideration, as Qsymia is typically studied in patients with obesity. 1, 2

Tirzepatide 3

Tirzepatide dosing is standardized and not weight-based:

  • Starting dose: 2.5 mg subcutaneously once weekly for 4 weeks 3
  • Escalation: Increase by 2.5 mg increments every 4 weeks 3
  • Maintenance doses: 10 mg or 15 mg once weekly 3

Given this patient's significantly low body weight (35.9 kg), tirzepatide would likely be contraindicated unless there is a specific medical indication, as it is designed for weight management in overweight/obese patients. 3

Critical Considerations for This Patient

This patient's weight of 35.9 kg is significantly below normal for a 26-year-old male (BMI likely <18.5), which raises important clinical concerns:

  • Weight management medications like Qsymia and tirzepatide are contraindicated in underweight patients 1, 2, 3
  • For tuberculosis treatment, standard weight-based dosing applies, but close monitoring for adverse effects is essential given lower body mass 1
  • Any medication dosing in an underweight adult requires careful consideration of drug distribution, metabolism, and potential toxicity 4

Please specify which medication you need dosing for, and I can provide more targeted guidance.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Qsymia Dosing and Administration

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Guideline

Tirzepatide Dosing and Treatment Plan for Weight Loss

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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