The Patent Trial and Appeal Board upheld US Patent 8,642,012 “Methods of Treatment Using AmmoniaScavenging Drugs” owned by Horizon Therapeutics LLC, which claims methods for treating a patient having a urea cycle disorder using a phenylacetic acid (PAA) prodrug [Glycerol phenylbutyrate (Ravicti®)]. Par Pharmaceutical Inc. and Lupin Ltd. had challenged the claims on obviousness grounds.
Claim 1. A method of treating a patient having a urea cycle disorder comprising (a) determining a target urinary phenylacetyl glutamine (PAGN) output (b) calculating an effective initial dosage of phenylacetic acid (PAA) prodrug selected from glyceryl tri-[4phenylbutyrate] (HPN-100) and phenylbutyric acid (PBA) or a pharmaceutically acceptable salt of PBA, wherein the effective dosage of PAA prodrug is calculated based on a mean conversion of PAA prodrug to urinary PAGN of about 60%; and (c) administering the effective initial dosage of PAA prodrug to the patient.
