Which medication should not be taken together with grapefruit juice?

Grapefruit juice is known to interact with certain medications due to its effect on the cytochrome P450 enzyme system, particularly CYP3A4. Cyclosporins, which are commonly used as immunosuppressants, are significantly affected by this interaction. When grapefruit juice is consumed, it can inhibit the metabolism of cyclosporins, leading to increased blood levels of the drug. This can enhance efficacy but also raises the risk of toxicity and adverse effects.

On the other hand, erythropoietin, iron supplements, and many antihypertensive medications do not exhibit significant interactions with grapefruit juice. Erythropoietin works through a different mechanism, iron supplements primarily function through absorption rather than metabolism, and many antihypertensives are metabolized via different pathways. Hence, the interaction with grapefruit juice is particularly relevant to cyclosporins, making it essential for patients on this medication to avoid grapefruit juice to maintain safe and effective treatment outcomes.