Pharmacokinetic changes in patients with oedema

Area of Science:

• Pharmacology and Clinical Pharmacy
• Drug Metabolism and Pharmacokinetics
• Internal Medicine

Background:

• Pharmacokinetics of drugs like furosemide, digoxin, theophylline, and ACE inhibitors can be altered in patients with edema.
• Distinguishing the effects of underlying diseases from edema per se on drug pharmacokinetics is challenging.
• Existing studies often lack clarity on whether disease or edema is the primary driver of pharmacokinetic changes.

Purpose of the Study:

• To review and analyze the impact of edema on the pharmacokinetics of commonly prescribed drugs.
• To differentiate the influence of edema from associated diseases on drug absorption, distribution, metabolism, and excretion.
• To identify drugs requiring dosage adjustments in edematous patients based on pharmacokinetic alterations.

Main Methods:

• Literature review of pharmacokinetic studies involving furosemide, digoxin, theophylline, and ACE inhibitors in edematous conditions.
• Analysis of reported changes in parameters such as bioavailability, Cmax, Tmax, protein binding, half-life, and clearance.
• Comparison of pharmacokinetic data between edematous patients and healthy volunteers.

Main Results:

• Furosemide absorption rate decreased in edema, but bioavailability remained unchanged; protein binding was lower in conditions like congestive heart failure (CHF) and nephrotic syndrome.
• Digoxin showed significant interindividual variability in CHF patients, necessitating cautious administration.
• Theophylline exhibited higher bioavailability and Cmax in hepatic cirrhosis and CHF patients, with decreased clearance and increased half-life.
• ACE inhibitor pharmacokinetics were influenced by associated diseases; perindopril dosage reduction is recommended in CHF, while other ACE inhibitors showed clinically irrelevant changes.
• Disease-induced disorders, rather than edema itself, were identified as the main cause of clinically relevant pharmacokinetic alterations.

Conclusions:

• Edema per se does not appear to cause clinically significant changes in the pharmacokinetics of most studied drugs.
• Associated diseases are the primary determinants of altered drug pharmacokinetics in edematous patients.
• Further research is warranted to fully elucidate the pharmacokinetic implications of edema and associated conditions.