Geriatric Drug Dosage Calculator
Calculate safe drug dosages for elderly patients considering age-related pharmacokinetic changes, organ function, and frailty.
Important Health Disclaimer
This calculator provides general health information based on standard medical formulas and WHO guidelines. Results are for informational and educational purposes only and should not be considered as professional medical advice, diagnosis, or treatment recommendations.
For health concerns, medical conditions, fitness plans, or dietary decisions, please consult with qualified healthcare professionals, licensed physicians, registered dietitians, or certified fitness trainers who can evaluate your individual health status and medical history.
Individual health needs vary significantly. These calculations are general estimates and may not be appropriate for everyone, especially those with existing medical conditions, pregnant women, children, or elderly individuals.
Not a substitute for professional medical advice
Patient Information
Clinical Status
Recommended Starting Dose
250 mg
"Start low, go slow" - 50% of adult dose
Dosing Strategy
Starting Dose: 250 mg (50% of normal)
Adjusted Target: 325 mg
Maximum Recommended: 325 mg
Adjustment Factors
Renal Factor: 75%
Hepatic Factor: 100%
Age-Related Renal Decline: 65%
Geriatric Considerations
- Increased receptor sensitivity may require lower doses
- Decreased total body water alters volume of distribution
- Reduced albumin increases free drug fraction
- Monitor for adverse effects at lower doses
Clinical Warning
Review Beers Criteria for potentially inappropriate medications. Consider drug-drug interactions, especially with polypharmacy. Titrate slowly based on response.
Age-Related Pharmacokinetic Changes
| Parameter | Change with Aging | Clinical Implication |
|---|---|---|
| Renal Function | Decreases 1%/year after 40 | Reduce doses of renally cleared drugs |
| Hepatic Metabolism | Phase I decreased, Phase II maintained | Avoid prodrugs, reduce hepatic-cleared drugs |
| Body Composition | Increased fat, decreased water | Lipophilic drugs accumulate longer |
| Serum Albumin | Decreased | Increased free drug for protein-bound drugs |
| Receptor Sensitivity | Increased for many drug classes | Enhanced effects at lower doses |
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