RAPAFLO is the brand name for silodosin, a selective antagonist of alpha-1 adrenoreceptors. The chemical name of silodosin is 1-(3-Hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-1H-indole-7-carboxamide and the molecular formula is C25H32F3N3O4 with a molecular weight of 495.53. The structural formula of silodosin is:

REBETOL is Schering Corporation's brand name for ribavirin, a synthetic nucleoside analogue (purine analogue). The chemical name of ribavirin is 1-?-D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide and has the following structural formula (see Figure 1).

Rivaroxaban, a factor Xa inhibitor, is the active ingredient in XARELTO Tablets with the chemical name 5-Chloro-N-({(5S)-2-oxo-3-[4-(3-oxo-4-morpholinyl)phenyl]-1,3-oxazolidin-5-yl}methyl)-2-thiophenecarboxamide. The molecular formula of rivaroxaban is C19H18ClN3O5S and the molecular weight is 435.89. The structural formula is:

Rebif® (interferon beta-1a) is a purified 166 amino acid glycoprotein with a molecular weight of approximately 22,500 daltons. It is produced by recombinant DNA technology using genetically engineered Chinese Hamster Ovary cells into which the human interferon beta gene has been introduced. The amino acid sequence of Rebif® (interferon beta-1a) is identical to that of natural fibroblast derived human interferon beta. Natural interferon beta and interferon beta-1a (Rebif® (interferon beta-1a) ) are glycosylated with each containing a single N-linked complex carbohydrate moiety.

REQUIP (ropinirole) is an orally administered non-ergoline dopamine agonist. It is supplied as the hydrochloride salt of ropinirole 4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one and has an empirical formula of C16H24N2O•HCl. The molecular weight is 296.84 (260.38 as the free base).

Actonel (risedronate sodium) tablets is a pyridinyl bisphosphonate that inhibits osteoclast-mediated bone resorption and modulates bone metabolism. Each Actonel (risedronate sodium) tablet for oral administration contains the equivalent of 5, 30, 35, 75, or 150 mg of anhydrous risedronate sodium in the form of the hemi-pentahydrate with small amounts of monohydrate. The empirical formula for risedronate sodium hemi-pentahydrate is C7H10NO7P2Na•2.5 H2O. The chemical name of risedronate sodium is [1-hydroxy-2-(3-pyridinyl)ethylidene]bis[phosphonic acid] monosodium salt. The chemical structure of risedronate sodium hemi-pentahydrate is the following:

Neupro® (Rotigotine Transdermal System) is a transdermal delivery system that provides rotigotine, a non-ergolinic dopamine agonist. When applied to intact skin, Neupro (rotigotine transdermal system) is designed to continuously deliver rotigotine over a 24-hour period.

Ruxolitinib phosphate is a kinase inhibitor with the chemical name (R)-3-(4-(7H-pyrrolo[2,3d]pyrimidin-4-yl)-1H-pyrazol-1-yl)-3-cyclopentylpropanenitrile phosphate and a molecular weight of 404.36. Ruxolitinib phosphate has the following structural formula:

RELAFEN (nabumetone) is a naphthylalkanone designated chemically as 4-(6-methoxy-2-naphthalenyl)-2-butanone. It has the following structure:

MYCOBUTIN Capsules contain the antimycobacterial agent rifabutin, which is a semisynthetic ansamycin antibiotic derived from rifamycin S. MYCOBUTIN (rifabutin) Capsules for oral administration contain 150 mg of rifabutin, USP, per capsule, along with the inactive ingredients microcrystalline cellulose, magnesium stearate, red iron oxide, silica gel, sodium lauryl sulfate, titanium dioxide, and edible white ink.