Medication Dosing for 17-Year-Olds
For a 17-year-old patient, medication dosing should follow adult dosing recommendations, as adolescents aged 12 years and older are physiologically mature and differ from adults primarily in size rather than drug metabolism or clearance.
General Dosing Principles
Adolescents 17 years of age should receive adult doses for most medications, as children aged 2 years and older are essentially similar to adults in terms of drug elimination and differ only in size 1. After 6 months of age, body surface area (BSA) becomes a reliable marker for drug dosing, and by adolescence, standard adult dosing applies 2.
Specific Medication Examples from Guidelines
Tuberculosis Treatment
- Isoniazid: 5 mg/kg daily (maximum 300 mg) or 15 mg/kg twice weekly (maximum 900 mg) 3
- Rifampin: 10 mg/kg daily (maximum 600 mg) or 10 mg/kg twice/three times weekly (maximum 600 mg) 3
- Ethambutol: 15-20 mg/kg daily (maximum 1.0 g) or 50 mg/kg twice weekly (maximum 4 g) 3
Respiratory Medications
- Azithromycin (for NTM or respiratory infections): For adolescents with body weight ≥46 kg, the dose is 500 mg once daily 3
- Albuterol: Adult dosing applies for adolescents 12 years and older 3
Influenza Antivirals
- Oseltamivir: 75 mg twice daily for treatment; 75 mg once daily for prophylaxis 3
- Zanamivir: Two inhalations (10 mg total) twice daily 3
- Amantadine/Rimantadine: 200 mg/day (100 mg twice daily) for adolescents >10 years weighing >40 kg 3
Psychiatric Medications
- Fluoxetine: Initial dose 10-20 mg/day in the morning, with potential increase to maximum 80 mg/day 4
- Haloperidol (for acute agitation): 5-10 mg IM/PO for older adolescents >16 years 3
- Lorazepam: 0.05-0.15 mg/kg (maximum 5 mg per dose) 3
Emergency Medications
- Atropine: 0.5 mg minimum dose, up to 1.0 mg maximum single dose for adolescents 3
- Epinephrine: Adult dosing (1 mg IV/IO for cardiac arrest) 3
- Amiodarone: 5 mg/kg IV/IO (maximum 300 mg) for ventricular arrhythmias 3
Important Caveats
Weight-Based Considerations
- For adolescents weighing <40 kg, weight-based dosing (5 mg/kg/day) should be used for certain medications like amantadine and rimantadine, regardless of age 3
- Atomoxetine dosing for adolescents >70 kg follows adult titration patterns: 40 mg → 60 mg → 80 mg/day every 7-14 days 5
Organ Function Adjustments
- Renal impairment: Dose reductions are necessary for renally cleared drugs; for example, hydroxyzine should be reduced by half in renal impairment 6
- Hepatic impairment: Lower doses should be considered for hepatically metabolized drugs 3
Formulation Considerations
- Adolescents can typically swallow tablets and capsules, eliminating the need for liquid formulations required in younger children 6
- Dry powder inhalers and metered-dose inhalers can be used effectively in this age group 3
Monitoring Requirements
Baseline assessments before initiating chronic medications should include: blood pressure, pulse, height, weight, and relevant laboratory tests (CBC, liver function tests, renal function tests) 3, 5. Therapeutic drug monitoring may be required for medications with narrow therapeutic indices, such as antituberculosis drugs 3.