Lisinopril, an ACE inhibitor, lowers blood pressure by blocking the production of angiotensin II, a potent vasoconstrictor. This leads to vasodilation and reduced blood volume.
Indomethacin, a nonsteroidal anti-inflammatory drug (NSAID), inhibits the production of prostaglandins, which play a crucial role in regulating kidney function and blood pressure. Specifically, prostaglandins counterbalance the effects of angiotensin II, promoting vasodilation and increasing sodium excretion.
Indomethacin’s Impact on Lisinopril’s Action
By reducing prostaglandin production, indomethacin can diminish this counterbalance. Consequently, the blood pressure-lowering effect of lisinopril may be reduced or even reversed, potentially leading to higher blood pressure. This interaction is more pronounced in patients with pre-existing renal impairment or heart failure.
Specific Physiological Effects
The interaction primarily affects the renin-angiotensin-aldosterone system (RAAS). Indomethacin’s interference with prostaglandin synthesis reduces the kidney’s ability to excrete sodium and water, increasing blood volume. This effect can negate lisinopril’s ability to lower blood pressure effectively.
| Lisinopril | Inhibits ACE, reducing angiotensin II | Decreases blood pressure | Reduced effectiveness due to indomethacin’s interference with prostaglandin production |
| Indomethacin | Inhibits prostaglandin synthesis | Can increase blood pressure (indirectly) | Reduces the blood pressure-lowering effect of lisinopril |
Monitoring blood pressure closely is crucial when using these drugs concurrently. Your doctor might adjust dosages or consider alternative medications to minimize risks.
