Impact of ACEi and ARBs on Lung Function in Patients with Hypertension

Differences in Mechanism of Action

Angiotensin II increases blood pressure through its effect on the contraction of smooth muscle in the vascular wall. To therapeutically influence hypertension, ACEi and ARBs were synthesized, which act antagonistically against the vasoconstrictive effect of angiotensin II.

ACEi achieve this by inhibiting the conversion of inactive angiotensin I to active angiotensin II. However, ACE is an enzyme that also affects the metabolism of other substances, such as bradykinin and tachykinins. The accumulation of these substances can—in addition to some beneficial effects—cause a dry cough (the most common adverse effect of ACEi) or worsen lung function.

ARBs achieve their antihypertensive effect by blocking the AT₁ receptors for angiotensin II, preventing the binding of angiotensin II to these receptors. This class of antihypertensives bypasses the side effects of ACEi, such as dry cough or angioedema, because they do not interfere with the formation of angiotensin II and the breakdown of kinins. However, it was not clear until now whether ARBs also affect lung function.

Evaluated Patient Population

The authors of the cited study included patients with hypertension aged 48–66 years treated for at least 1 year with ACEi (captopril, enalapril, or lisinopril) or ARB (losartan or valsartan) and a control group of healthy individuals. Exclusion criteria included smoking, the presence of bronchial asthma, chronic obstructive pulmonary disease (COPD), tuberculosis, heart or lung disease, and a history of chest surgery, trauma, or deformities.

All included patients underwent spirometry with the same specialist in the morning. Measured parameters included forced expiratory volume in one second (FEV₁), forced vital capacity (FVC, the maximum volume of air that can be forcefully exhaled after maximum inhalation), and FEV₁% (the ratio of FEV₁ to FVC). Each test was repeated 3 times to achieve the best patient cooperation.

A total of 241 individuals were included, of which 190 were patients with hypertension (average age 58 years, 67% men, average weight 76 kg) and 51 were controls (average age 52 years, 76% men, average weight 80 kg).

Results

Patients treated with ACEi showed significantly lower FEV₁ values compared to the control group: 1.7–2.4 with individual ACEi vs. 3.5 in the control group (p < 0.05). In patients treated with ARBs, the average FEV₁ was 3.2, which is an insignificant difference compared to the controls.

ACEi use was also associated with a significant decrease in FVC compared to controls (2.0–2.8 vs. 3.3; p < 0.05). This decrease was not observed in patients treated with ARBs (FVC 3.9).

The FEV₁% value was significantly changed compared to controls with the use of ACEi (78.4–83.6 vs. 87.0; p < 0.05) and ARBs (82.2 with valsartan, 83.1 with losartan vs. 87.0; p < 0.05).

Conclusion

The results of the cited study suggest that ARBs do not exhibit adverse effects on the normal respiratory function of patients with hypertension, unlike ACEi which can reduce FEV₁ and FVC. Based on these findings, sartans could be safer in terms of preserving lung function and it should be further studied whether they should be preferred in patients prone to respiratory adverse effects.

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Source: Jabbar A. S., Neamah N. F., Al-Darraji A. H. Comparative effects of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers on pulmonary function in hypertensive patients. J Basic Clin Physiol Pharmacol 2021 Mar 15; 33 (2): 207−212, doi: 10.1515/jbcpp-2020-0243.