From the Guidelines
Captopril can affect zinc levels in the body by increasing urinary zinc excretion, potentially leading to reduced zinc levels with long-term use. The mechanism involves captopril's sulfhydryl group binding to zinc, forming complexes that are then excreted through the kidneys. Patients on long-term captopril therapy, particularly those taking higher doses (over 50 mg daily) or who have been on the medication for several months, may be at increased risk for zinc deficiency. Signs of zinc deficiency include impaired wound healing, taste alterations, hair loss, and decreased immune function.
- Patients taking captopril chronically should consider monitoring their zinc status, especially if they develop symptoms suggestive of deficiency.
- In some cases, zinc supplementation of 15-30 mg elemental zinc daily may be appropriate, but this should be taken at a different time than captopril to avoid interference with drug absorption.
- The zinc-chelating property of captopril is not shared by all ACE inhibitors, so those concerned about zinc status might discuss with their healthcare provider whether a non-sulfhydryl ACE inhibitor would be an appropriate alternative 1.
From the Research
Captopril Effect on Zinc Levels
- Captopril, an Angiotensin-Converting Enzyme (ACE) inhibitor, has been studied for its potential impact on zinc levels in the body 2, 3, 4, 5, 6.
- A study published in 1987 found that serum zinc levels were unaffected by effective captopril treatment of hypertension, suggesting that zinc depletion is unlikely to be a consequence of long-term exposure to captopril 2.
- However, a 1990 study found that captopril-treated patients had significantly increased 24-hour urinary zinc excretion and decreased red blood cell zinc values compared to other groups, indicating potential renal zinc loss and RBC zinc depletion 3.
- Another study published in 1988 found that long-term, high-dose captopril recipients had significantly higher taste detection and recognition thresholds, lower plasma zinc levels, and higher urinary zinc excretion compared to controls, suggesting a link between captopril therapy and changes in zinc metabolism 4.
- A 1995 study found that serum zinc levels decreased significantly in patients after 3 and 6 months of treatment with captopril, atenolol, or verapamil, regardless of the drug used, although intraerythrocyte zinc was not significantly affected 5.
- A 2006 review discussed the potential impact of medications commonly used in the management of heart failure, including ACE inhibitors like captopril, on zinc metabolism, highlighting conflicting evidence and the need for further investigation 6.