Which of the following medications has possible respiratory side effects?

Timolol is a beta-blocker that can have respiratory side effects, particularly in individuals with pre-existing respiratory conditions such as asthma or chronic obstructive pulmonary disease (COPD). As a non-selective beta-blocker, it can block both beta-1 and beta-2 adrenergic receptors. The blockade of beta-2 receptors in the lungs can lead to bronchoconstriction, which may result in wheezing, shortness of breath, or exacerbation of asthma symptoms.

This side effect is particularly important to consider when prescribing Timolol, especially in patients who have a history of respiratory issues, as it may provoke adverse reactions. In clinical practice, this emphasizes the need for careful patient assessment and monitoring when using Timolol in individuals with compromised respiratory function.

Other medications listed, like Cyclopentolate and Pilocarpine, primarily affect ocular functions and have minimal or negligible effects on respiratory function. Zinc sulphate is usually used for dietary supplementation or to treat deficiencies and does not have known respiratory side effects.