What is the proper administration advice for Nitrobid (topical ointment)?

B is the correct answer because maintaining a nitrate-free period of 10-12 hours is essential when using Nitrobid (topical ointment) to prevent tolerance to nitrates. If nitroglycerin is applied continuously or too frequently, the body can become accustomed to its effects, reducing its efficacy in managing angina and potentially leading to withdrawal symptoms.

This nitrate-free interval allows the body to regain sensitivity to the medication, ensuring its effectiveness when needed. Proper administration involves careful timing that aligns with the recommended use to mitigate side effects and maximize therapeutic benefits.

The other options do not appropriately reflect safe and effective practices for this medication. Using the ointment every hour or applying it continuously could lead to overdose or reduced effectiveness over time, and only applying it when experiencing chest pain would not provide the necessary prophylactic benefits for managing angina symptoms in a patient with a known condition.