What risk is associated with administering H-1 antihistamines together with opioids?

What risk is associated with administering H-1 antihistamines together with opioids?

• A. Respiratory depression and hypotension
• B. Hypertension and tachycardia
• C. Hyperglycemia
• D. Increased urine production

Answer: (A)

The main idea is that combining CNS-depressant medications increases the risk of significant respiratory and hemodynamic compromise. H-1 antihistamines, especially sedating ones like diphenhydramine, add to the respiratory-depressant effects of opioids. Together, they can blunt the respiratory drive and cause lower blood pressure, leading to respiratory depression and hypotension. This combination is particularly concerning in antepartum care because maternal hypoventilation or hypotension can reduce placental perfusion and fetal oxygenation. The other options don’t fit the usual pharmacologic effects here: hypertension and tachycardia are not the typical result of adding an antihistamine to an opioid, hyperglycemia isn’t expected, and increased urine production isn’t a common effect. If these drugs must be used together, monitor respiratory status and blood pressure closely, and consider alternatives when possible.

The main idea is that combining CNS-depressant medications increases the risk of significant respiratory and hemodynamic compromise. H-1 antihistamines, especially sedating ones like diphenhydramine, add to the respiratory-depressant effects of opioids. Together, they can blunt the respiratory drive and cause lower blood pressure, leading to respiratory depression and hypotension. This combination is particularly concerning in antepartum care because maternal hypoventilation or hypotension can reduce placental perfusion and fetal oxygenation. The other options don’t fit the usual pharmacologic effects here: hypertension and tachycardia are not the typical result of adding an antihistamine to an opioid, hyperglycemia isn’t expected, and increased urine production isn’t a common effect. If these drugs must be used together, monitor respiratory status and blood pressure closely, and consider alternatives when possible.