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ZANTAC® 75 Glaxo Wellcome Ranitidine HCl Histamine H2-receptor Antagonist Action And Clinical Pharmacology: Ranitidine is an antagonist of histamine at gastric H2-receptor sites. Thus, ranitidine inhibits both basal gastric secretion and gastric acid secretion induced by histamine, pentagastrin and other secretagogues. Inhibition of gastric acid secretion has been observed following i.v., intraduodenal and oral administration of ranitidine. This response is dose-related, a maximum response being achieved at an oral dose…

X-PREP® Purdue Frederick Standardized Sennosides Diagnostic Aid Indications And Clinical Uses: A potent cathartic to be used only for evacuation of the colon prior to contrast radiography of the gastrointestinal tract, other abdominal radiography, or examinations where a clear colon is essential for proper visualization. Also indicated prior to surgery of the colon or rectum. Contra-Indications: The “acute abdomen”. Dosage And Administration: Adults: At 10 a.m. on the day prior…

VITAMIN D General Monograph Vitamin Action And Clinical Pharmacology: Vitamin D is a fat-soluble vitamin and has properties of both vitamins and minerals. The term vitamin D collectively refers to a group of structurally similar chemicals and their metabolites which includes alfacalcidol (1hydroxycholecalciferol), calcitriol (1,25-dihydroxycholecalciferol), cholecalciferol (vitamin D3), dihydrotachysterol (DHT) and ergocalciferol (vitamin D2). These agents have antirachitic properties. The biologic activity of 40 IU vitamin D equals that of…

VITAMIN B6 General Monograph Pyridoxine Vitamin Pharmacology: Vitamin B6 is a water soluble B complex vitamin which is present in many foods as pyridoxine, pyridoxal and pyridoxamine. These forms of vitamin B6 are converted in vivo to pyridoxal phosphate and pyridoxamine phosphate, which are essential coenzymes in the metabolism of certain amino acids such as tryptophan, in carbohydrate and lipid metabolism, and in the synthesis of heme and GABA, an…

VITAMIN K General Monograph, Phytonadione Hypoprothrombinemia Therapy Action And Clinical Pharmacology: Vitamin K compounds are fat soluble naphthoquinones. Phytonadione (vitamin K1) and vitamin K2 occur in a variety of natural materials and are synthesized by certain bacteria in the gastrointestinal tract; however, commercially prepared phytonadione is synthetically produced. Phytonadione possesses essentially the same type and degree of activity as naturally occurring vitamin K1. Vitamin K is necessary for synthesis in…

VITAMIN A ACID Dermik Laboratories Canada Tretinoin Acne Therapy Action And Clinical Pharmacology: The interest in oral vitamin A in the treatment of acne started some 30 years ago following publication of a report by Straumfjord and theoretical support for the use of the vitamin in the reduction of hyperkeratosis came from basic science investigations. Hunter and Pinkus showed a reduction in the number of keratinocytes in the human stratum…

VITAMIN A General Monograph, Vitamin Pharmacology: The term vitamin A is applied to a number of substances with very similar structure and similar activity. The principal and most active substance is all-trans retinol (vitamin A alcohol). Vitamin A activity is assayed biologically and 1 IU equals 1 USP unit which is equal to 0.3 µg of all-trans retinol or 0.6 g of beta-carotene. One retinol equivalent (RE) is the specific…

VITAMIN B1 General Monograph Thiamine Vitamin Pharmacology: Vitamin B1 is a water soluble B complex vitamin. In vivo, vitamin B1 combines with adenosine triphosphate (ATP) to form thiamine pyrophosphate, also known as cocarboxylase, a coenzyme. Its role in carbohydrate metabolism is the decarboxylation of pyruvic acid and alpha-ketoacids to acetaldehyde and carbon dioxide. Increased levels of pyruvic acid in the blood indicate vitamin B1 deficiency. Vitamin B1 depletion can occur…

VITAMIN B2 General Monograph Riboflavin Vitamin Pharmacology: Vitamin B2 is a water-soluble, B complex vitamin. It is required for tissue respiration and is also indirectly involved in maintaining erythrocyte integrity. Vitamin B2 deficiency often accompanies pellagra and other B vitamin deficiency states and is also associated with conditions causing negative protein balance, such as chronic diarrhea, malabsorption syndrome, diabetes mellitus and chronic debilitating diseases. Deficiency is manifested by angular stomatitis,…

VIAGRA® (sildenafil citrate) Tablets DESCRIPTION VIAGRA®, an oral therapy for erectile dysfunction, is the citrate salt of sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Sildenafil citrate is designated chemically as 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine citrate and has the following structural formula: Sildenafil citrate is a white to off-white crystalline powder with a solubility of 3.5 mg/mL in water and a molecular weight of 666.7. VIAGRA® (sildenafil citrate)…