Table 5 Summary of steps involved in a sapropterin therapy trial

Screening Phase

• Diet alone

• Food diary

• Determination of baseline Phe tolerance (PheTol₀)

• Determination of the baseline quantity of protein from the amino-acid mixture (amino-acid supplement [AAS₀])

• Determination of the baseline blood Phe concentration (Phe₀)

Test Phase

• Sapropterin 10–20 mg/kg per day

• Food diary

• Determination of the Phe tolerance on therapy (PheTol₁)

• Determination of the quantity of protein from the amino-acid mixture on therapy (AAS₁)

• Determination of the Phe concentration on therapy (Phe₁)

• Continuing the test phase based on the algorithm until steady state is reached

Evaluation

• Calculate the differences:

­ PheTol_x – PheTol₀

­ AAS_x – AAS₀

­ Phe_x – Phe₀

• Evaluation and critical benefit analysis in the team