Background Sodium phenylbutyrate (NaPB), a treatment for urea cycle disorders, has an extremely unpleasant, bitter taste which can compromise compliance and metabolic control, particularly in children. Attempts to mask the taste in food or drinks are unsuccessful and can lead to feeding aversion further complicating management of these serious disorders.

Objectives A new, taste-masked, coated-granule formulation (Luc 01) has been developed and the taste characteristics, dissolution and bioequivalence, including taste, safety and tolerability, of this form were compared to the available, licensed granule product.

Results The in vitro taste profile of NaPB indicated a highly stimulant molecule. Luc 01 released NaPB only after a lag-time of ∼10 s followed by a very slow release during several minutes compared with complete, immediate release of NaPB from licensed granules. Pharmacokinetic evaluation demonstrated bioequivalence of a 5 g dose of both products in 13 healthy volunteers. No statistical difference was observed for maximal plasma concentration or area under the plasma concentration-time. Luc 01 was significantly more acceptable, less bitter and less salty (p<0.01).

Conclusions In vitro and in vivo taste profiles indicate that Luc 01 can be swallowed before stimulation of taste receptors by NaPB and is bioequivalent to the licensed product. The availability of Luc 01 should improve compliance/efficacy of NaPB treatment and alleviate the burden of administration particularly in children.