New River: Studies show NRP104 less euphoric than other ADHD drugs

By E. Janene Geiss

Philadelphia, June 19 - New River Pharmaceuticals Inc. announced Sunday results from two clinical abuse liability studies on NRP104, which showed the drug to be less euphoric and more dysphoric than d-amphetamine in pediatric patients in treatment for attention-deficit/hyperactivity disorder (ADHD).

The results were from two clinical abuse liability studies on NRP104. The drug candidate is the subject of a New Drug Application filed with the Food and Drug Administration on Dec. 6, seeking approval for three therapeutic doses (30, 50 and 70 mg) of NRP104 for the treatment of ADHD in pediatric populations, according to a company news release.

The A01 study was a single-blind, placebo- and active-controlled, single-dose escalation study of NRP104 (up to 150 mg) to evaluate safety, tolerability and abuse liability in healthy adult volunteers with histories of stimulant abuse.

The subjective and behavioral effects for NRP104 overall in doses comparable to or greater than d-amphetamine (40 mg) tended to be less euphoric and more dysphoric than d-amphetamine (40 mg), with a later peak effect, officials said.

There was no apparent dose-response relationship in either the subjective effects or cardiovascular effects in the NRP104 dose range of 30 mg to 150 mg.

The systemic exposure to d-amphetamine was dose-proportional for NRP104 in the range of 30 mg to 130 mg, following a single dose administration. However, the increase in overall exposure was significantly attenuated between the 130 mg dose and the 150 mg dose, officials said.

Doses of NRP104 from 30 mg to 150 mg were safe and well-tolerated in the population of stimulant abusers, officials said.

The A03 study evaluated the likeability of NRP104 (50 mg, 100 mg and 150 mg) compared to a placebo and two active controls in stimulant abusers.

The two active controls in the study were d-amphetamine 40 mg, a Schedule II stimulant, and diethylpropion 200 mg, a Schedule IV stimulant.

On a mole weight basis, the amphetamine-free base content in NRP104 100 mg is equal to the amphetamine-free base content in d-amphetamine sulfate 40 mg, and the diethylpropion 200 mg is expected to provide the same level of subjective and behavioral effects as d-amphetamine sulfate 40 mg, officials said.

Each of the three doses, one dose of d-amphetamine 40 mg, one dose of diethylpropion hydrochloride 200 mg and one dose of NRP104 100mg, produced liking effects that were greater than a placebo with respect to the primary endpoint, a Drug Rating Questionnaire Subject Liking Score.

However, the mean difference of the liking score from placebo was not statistically significant for the NRP104 100 mg dose when compared to that of a placebo.

By contrast, the differences of the liking scores from a placebo were statistically significant for both d-amphetamine 40 mg and diethylpropion hydrochloride 200 mg, officials said.

In a pairwise comparison analysis, the liking effects of NRP104 100 mg were less than those of d-amphetamine 40 mg and diethylpropion 200 mg to a statistically significant extent.

The results were presented Sunday at the annual meeting of the College on Problems of Drug Dependence in Scottsdale, Ariz.

NRP104 is the subject of a collaboration agreement between New River and Shire plc.

New River is a Radford, Va., specialty pharmaceutical company.

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