Clinical pharmacological studies with doxazosin

Area of Science:

• Pharmacology
• Clinical Pharmacology
• Drug Metabolism and Pharmacokinetics

Background:

• Doxazosin is an alpha-1 adrenoceptor antagonist used clinically.
• Understanding its pharmacokinetics in different age groups is crucial for safe and effective use.

Purpose of the Study:

• To review the clinical pharmacology of doxazosin.
• To compare its pharmacokinetic and pharmacodynamic properties in young and elderly subjects.

Main Methods:

• Oral and intravenous administration of doxazosin to young and elderly normotensive subjects.
• Measurement of bioavailability, elimination half-lives, volume of distribution, and clearance.
• Assessment of blood pressure and heart rate changes.
• Pharmacodynamic studies using phenylephrine to confirm alpha-1 adrenoceptor antagonism.

Main Results:

• Doxazosin showed similar bioavailability and elimination half-lives in young and elderly subjects.
• Elderly subjects exhibited a higher apparent volume of distribution and clearance.
• Blood pressure reduction was most pronounced in the standing position, with a delayed onset of maximum effect.
• Heart rate increase was significant in young subjects but attenuated in the elderly.
• Doxazosin confirmed alpha-1 adrenoceptor antagonist activity.

Conclusions:

• Doxazosin's pharmacokinetic profile is comparable between young and elderly individuals.
• Pharmacodynamic effects, particularly heart rate response, differ between age groups.
• Concentration-effect analysis can correlate doxazosin levels with its hypotensive and antagonist effects.