Arbaclofen placarbil

399.86584

399.87

-0

W89H91R7VX

DTXSID40233754

102

4.2

P264, P270, P301+P312, P330, P501

H302

|Warning|H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]|P264, P270, P301+P312, P330, and P501|The GHS information provided by 1 company from 1 notification to the ECHA C&L Inventory.

Investigated for the treatment of spasticity in multiple sclerosis, acute back spasms, and GERD.

Endogenous compounds and drugs that bind to and activate GABA-B RECEPTORS. (See all compounds classified as GABA-B Receptor Agonists.)|A heterogeneous group of drugs used to produce muscle relaxation, excepting the neuromuscular blocking agents. They have their primary clinical and therapeutic uses in the treatment of muscle spasm and immobility associated with strains, sprains, and injuries of the back and, to a lesser degree, injuries to the neck. They have been used also for the treatment of a variety of clinical conditions that have in common only the presence of skeletal muscle hyperactivity, for example, the muscle spasms that can occur in MULTIPLE SCLEROSIS. (From Smith and Reynard, Textbook of Pharmacology, 1991, p358) (See all compounds classified as Muscle Relaxants, Central.)

Unlike baclofen, absorption of R-baclofen(arbaclofen) is not limited to the upper small intestine. The ability of arbaclofen to be absorbed throughout the gastrointestinal tract allowed for the development of the sustained release formulation, arbaclofen placarbil (AP). In one study of AP absorption in 10 healthy volunteers, one 20mg oral dose of AP, in the presence of food, resulted in a Tmax of 5.05h. The oral bioavailability of R-baclofen in rats when AP was dosed at 10mg/kg was 44 ± 12%, and when dosed at 1mg/kg, oral bioavailability was 68 ± 6%. In monkeys and dogs, the oral bioavailability of R-baclofen when AP was orally dosed was high: 94 ± 16%, and 92 ± 7%, respectively. In comparison, when oral R-balofen was dosed oral bioavailability was 39 ± 21% in monkeys and 49 ± 20% in dogs. Colonic absorption studies measuring R-baclofen bioavailability post intracolonic dosing in rats and monkeys, have revealed low bioavailability with the administration of R-baclofen (7 ± 3% and 3 ± 2%, respectively), and significantly higher R-baclofen bioavailability with intracolonic dosing of AP suspension ( 37 ± 9% and 37 ± 15%, in rats and monkeys respectively). Intracolonic dosing of AP suspension also resulted in high biolavailability of R-baclofen in dogs (77 ± 23%). Absorption throughout the intestine is both passive and active and occurs via the monocarboxylate type 1 transporter.|84-88% renal elimination as R-baclofen. Less than 1% fecal elimination. (2)|Radioactive labeling has shown AP to be widely distributed throughout the body. Tissue distribution occurs mostly to the kidneys and liver.|Blood clearance of an IV bolus of AR in rats resulted in a total blood clearance of 15.81 ± 10.2 L/h/kg in rats. In comparison, blood clearance of an IV bolus of R-baclofen in rats, monkeys, and dogs, resulted in half lives ranging from 1.6-3.4hours, with total blood clearances reported to be 0.51± 0.13L/h/kg in rats, 0.31±0.11L/h/kg in monkeys, and 0.24L±0.01L/h/kg in dogs. (2) In studied utilizing radioactive tracers attached to R-baclofen, 97% of radioactivity was recovered in the urine.

In experimental studies using human liver S9 Arbaclofen placarbil was not shown to be a substrate for CYP1A2, CYP2C19, CYP2D6, CYP2E1, and CYP3A4. Arbaclofen placarbil, the acyloxyalkyl carbamate prodrug of R-arbaclofen, is believed to undergo hydrolysis by the esterase enzyme human carboxylesterase-2 into the parent amine, R-baclfen. Carbon dioxide, isobutyric acid, isobutyraldehyde, are also expected to be produced in equimolar quantities. The productions of isobutyric acid has been confirmed in vitro untilizing mass spectrometry and gas chromatography.

IV bolus administration of AP to rats showed that AP was converted to R-baclofen with a half life of 6 minutes.

R-baclofen is postulated to aid in spasticity by acting as an agonist of the inhibitory gamma aminobutyric acid neurotransmission pathway.

4-chloro-beta-((((2-methyl-1-(2-methyl-1-oxopropoxy)propoxy)carbonyl)amino)methyl)benzenepropanoic acid