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Propylthiouracil disposition in older hypothyroid patients
D S Sitar1, A Abu-Bakare, R J Gardiner
1Division of Clinical Pharmacology, Montreal General Hospital, Winnipeg, Canada.
Pharmacology
|January 1, 1988
Summary
Propylthiouracil (PTU) clearance is lower in severe hypothyroidism, with higher distribution and longer half-life in older patients. These factors suggest hypothyroidism and chronic drug use impact PTU
Area of Science:
- Pharmacology
- Endocrinology
- Clinical Pharmacy
Background:
- Propylthiouracil (PTU) is a key medication for managing hyperthyroidism.
- Understanding PTU's pharmacokinetic profile is crucial for effective treatment, especially in patients with altered thyroid states.
Purpose of the Study:
- To investigate the pharmacokinetic disposition of propylthiouracil (PTU) in patients with severe hypothyroidism.
- To determine the relationship between disease severity and PTU pharmacokinetics.
Main Methods:
- A single oral dose of PTU was administered to 6 severely hypothyroid patients.
- Plasma concentrations of PTU were measured over time.
- Thyroid-stimulating hormone (TSH) levels were used to assess disease severity.
Main Results:
- Plasma clearance of PTU was inversely related to the severity of hypothyroidism (indicated by TSH levels).
- A trend towards increased apparent volume of distribution and plasma half-life of PTU was observed with increasing age.
- The apparent volume of distribution for PTU was larger in hypothyroid patients compared to euthyroid or hyperthyroid individuals.
Conclusions:
- Severe hypothyroidism significantly affects PTU pharmacokinetics, leading to reduced clearance.
- Age and hypothyroidism are potential factors influencing PTU's distribution and elimination.
- These findings highlight the need to consider patient-specific factors for optimizing PTU dosing.