What drug class should be avoided with phenyl 10% due to the risk of hypertensive crisis?

The correct answer is that MAOIs (monoamine oxidase inhibitors) should be avoided with phenylephrine 10% due to the risk of hypertensive crisis. Phenylephrine is a sympathomimetic drug that can increase blood pressure by stimulating alpha-adrenergic receptors, leading to vasoconstriction. MAOIs inhibit the breakdown of monoamines, including norepinephrine.

When MAOIs and phenylephrine are taken together, the potential for excessive norepinephrine levels can lead to a significant increase in blood pressure, resulting in a hypertensive crisis, which is a life-threatening condition. This interaction is well-documented, and individuals on MAOIs are advised to avoid substances like phenylephrine that can elevate blood pressure.

In contrast, while tricyclic antidepressants can also impact norepinephrine levels and may have some interactions with phenylephrine, the risk of hypertensive crisis is primarily associated with MAOIs. The other drug classes listed, such as selective serotonin reuptake inhibitors and beta-blockers, do not carry the same risk when taken with phenylephrine, making them less relevant to this specific concern.