Caverject and grapefruit: a real interaction?
Grapefruit is famous as the juice that interacts with medications, and the warning is real for a number of drugs. Whether it matters specifically for Caverject (Alprostadil) at 10mcg, 20mcg, 40mcg depends on whether the active ingredient Alprostadil is metabolised by CYP3A4 in the gut wall and how much that pathway contributes to first-pass metabolism.
The CYP3A4 mechanism
Grapefruit (and its juice) inhibits CYP3A4 enzymes in the gut wall, increasing the absorbed dose of medications metabolised by that enzyme. For drugs in the Erectile Dysfunction (ED) class that go through CYP3A4 first-pass metabolism, regular grapefruit consumption can raise plasma levels of Alprostadil by a clinically meaningful margin and amplify side effects.
What to do with Caverject
According to the prescribing information for Alprostadil, if grapefruit is flagged as an interaction, the safest practice is to avoid grapefruit entirely or to discuss timing with the prescriber. Alprostadil binds prostaglandin E receptors on smooth muscle of the corpus cavernosum, triggering cAMP-mediated relaxation of cavernosal smooth muscle independent of the nitric oxide pathway used by P… A small occasional serving may be tolerable; daily large servings around the time of Caverject dosing are not recommended at 10mcg, 20mcg, 40mcg.
Frequently asked questions
Can I eat grapefruit while on Caverject? ▾
For some Erectile Dysfunction (ED) medications, grapefruit is best avoided or limited because of CYP3A4 inhibition. Whether Caverject specifically is affected depends on Alprostadil; the prescribing information lists this. When in doubt, ask the pharmacist or check the patient leaflet.
How much grapefruit is too much with Caverject? ▾
For drugs where the interaction matters, even modest daily grapefruit intake (one whole grapefruit or one large glass of juice) can shift drug levels noticeably. For Caverject at 10mcg, 20mcg, 40mcg, individual tolerance varies; the cautious choice is to avoid grapefruit if any interaction is mentioned.
More on Caverject
- With alcoholCaverject and alcohol — is it safe to drink?
- With foodShould Caverject be taken with food?
- Side effectsCaverject side effects: common, rare and warning signs
- Dosage guideCaverject dosage guide: how much to take and when
- OnsetHow fast does Caverject start working?
- DurationHow long does Caverject last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.