How to calculate the onset and offset of a chemical medicine that is XR?

Question

and what is the formula for determining this?

Answer 1

Focalin™ XR (dexmethylphenidate hydrochloride) extended-release capsules is an extended-release formulation of dexmethylphenidate with a bi-modal release profile. Focalin™ XR uses the proprietary SODAS® (Spheroidal Oral Drug Absorption System) technology. Each bead-filled Focalin XR capsule contains half the dose as immediate-release beads and half as enteric-coated, delayed-release beads, thus providing an immediate release of dexmethylphenidate and a second delayed release of dexmethylphenidate. Focalin XR 5, 10, and 20 mg capsules provide in a single dose the same amount of dexmethylphenidate as dosages of 2.5, 5, or 10 mg of Focalin™ tablets given b.i.d.

Dexmethylphenidate hydrochloride, the d-threo enantiomer of racemic methylphenidate hydrochloride, is a central nervous system (CNS) stimulant.

Dexmethylphenidate hydrochloride is methyl (alpha)-phenyl-2-piperidineacetate hydrochloride, (R,R')-(+)-. Its empirical formula is C 14 H 19 NO 2 ·HCl. Its molecular weight is 269.77 and its structural formula is



Dexmethylphenidate hydrochloride is a white to off white powder. Its solutions are acid to litmus. It is freely soluble in water and in methanol, soluble in alcohol, and slightly soluble in chloroform and in acetone.

Inactive ingredients:    ammonio methacrylate copolymer, FD&C Blue #2 (5 mg strength), FDA/E172 yellow iron oxide (10 mg strength), gelatin, ink Tan SW-8010, methacrylic acid copolymer, polyethylene glycol, sugar spheres, talc, titanium dioxide, and triethyl citrate.

CLINICAL PHARMACOLOGY

Pharmacodynamics

Dexmethylphenidate hydrochloride, the active ingredient in Focalin™ XR (dexmethylphenidate hydrochloride) extended-release capsules, is a central nervous system stimulant. Dexmethylphenidate, the more pharmacologically active d -enantiomer of racemic methylphenidate, is thought to block the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase the release of these monoamines into the extraneuronal space. The mode of therapeutic action in Attention Deficit Hyperactivity Disorder (ADHD) is not known.