Why does the absorption rate of orally administered cyclosporine (an immunosuppressant) vary significantly between patients with similar dosages, especially post-digestive processing?

💡 Explanation

Cyclosporine's absorption depends significantly on CYP3A4 activity in the small intestine because this enzyme metabolizes the drug, reducing its bioavailability. Variations in enzyme levels between individuals, influenced by genetics and diet, result in highly variable absorption, therefore affecting drug efficacy, rather than consistent metabolism or predictable transit times.

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