Deskripsi
Diltiazem inhibits CYP3A4-mediated methylprednisolone metabolism, increasing methylprednisolone exposure and the risk of steroid side effects including immunosuppression, hyperglycaemia, and hypertension.
Mekanisme
Methylprednisolone is primarily metabolised by CYP3A4; diltiazem's CYP3A4 inhibition reduces clearance, increasing methylprednisolone AUC by approximately 50–80% in published pharmacokinetic studies.
Signifikansi Klinis
Patients on diltiazem who receive methylprednisolone pulses may experience prolonged immunosuppression and increased steroid side effects; particularly relevant in transplant recipients.
Penatalaksanaan
Consider reducing methylprednisolone dose by 30–50% when diltiazem is co-administered; monitor for steroid toxicity; be aware that the interaction reverses upon diltiazem discontinuation.