Sapropterininteractions

Table 4 includes drugs with clinically important drug interactions when administered with sapropterin dihydrochloride and instructions for preventing or managing them.

Table 4: Clinically Relevant Drug Interactions Levodopa Clinical Impact Sapropterin dihydrochloride may increase the availability of tyrosine, a precursor of levodopa. Neurologic events were reported postmarketing in patients receiving sapropterin and levodopa concomitantly for a non- PKU indication. Intervention Monitor patients for a change in neurologic status. Inhibitors of Folate Synthesis (e.g., methotrexate, valproic acid, phenobarbital, trimethoprim) Clinical Impact In vitro and in vivo nonclinical data suggest that drugs that inhibit folate synthesis may decrease the bioavailability of endogenous BH4 by inhibiting the enzyme dihydrofolate reductase, which is involved in the recycling (regeneration) of BH4. This reduction in net BH4 levels may increase Phe levels. Intervention Consider monitoring blood Phe levels more frequently during concomitant administration. An increased dosage of sapropterin dihydrochloride may be necessary to achieve a biochemical response. Drugs Affecting Nitric Oxide-Mediated Vasorelaxation (e.g., PDE-5 inhibitors such as sildenafil, vardenafil, or tadalafil) Clinical Impact Both sapropterin dihydrochloride and PDE-5 inhibitors may induce vasorelaxation. A reduction in blood pressure could occur; however, the combined use of these medications has not been evaluated in humans. Intervention Monitor blood pressure. Inhibitors of Folate Synthesis (e.g., methotrexate, valproic acid, phenobarbital, trimethoprim): Can decrease endogenous BH4 levels; monitor blood Phe levels more frequently and adjust sapropterin dihydrochloride dosage as needed. Drugs Affecting Nitric Oxide-Mediated Vasorelaxation (e.g., PDE-5 inhibitors): Potential for vasorelaxation; monitor blood pressure.