Zidovudine is a nucleoside reverse transcriptase inhibitor (NRTI) with activity against Human Immunodeficiency Virus Type 1 (HIV-1). Zidovudine is phosphorylated to active metabolites that compete for incorporation into viral DNA. They inhibit the HIV reverse transcriptase enzyme competitively and act as a chain terminator of DNA synthesis. The lack of a 3'-OH group in the incorporated nucleoside analogue prevents the formation of the 5' to 3' phosphodiester linkage essential for DNA chain elongation, and therefore, the viral DNA growth is terminated. Zidovudine, a structural analog of thymidine, is a prodrug that must be phosphorylated to its active 5′-triphosphate metabolite, zidovudine triphosphate (ZDV-TP). It inhibits the activity of HIV-1 reverse transcriptase (RT) via DNA chain termination after incorporation of the nucleotide analogue. It competes with the natural substrate dGTP and incorporates itself into viral DNA. It is also a weak inhibitor of cellular DNA polymerase α and γ. Zidovudine is used in combination with other antiretroviral agents for the treatment of human immunovirus (HIV) infections. Zidovudine is marketed as Retrovir.

Ursodiol tablets, USP are bile acids indicated for the treatment of patients with primary biliary cirrhosis. Ursodiol (Ursodeoxycholic acid), a naturally occurring hydrophilic bile acid, derived from cholesterol, is present as a minor fraction of the total human bile acid pool. Ursodeoxycholic acid reduces elevated liver enzyme levels by facilitating bile flow through the liver and protecting liver cells. The main mechanism if anticholelithic. Although the exact process of ursodiol's anticholelithic action is not completely understood, it is thought that the drug is concentrated in bile and decreases biliary cholesterol by suppressing hepatic synthesis and secretion of cholesterol and by inhibiting its intestinal absorption. The reduced cholesterol saturation permits the gradual solubilization of cholesterol from gallstones, resulting in their eventual dissolution. In addition to the replacement and displacement of toxic bile acids, other mechanisms of action include cytoprotection of the injured bile duct epithelial cells (cholangiocytes) against toxic effects of bile acids, inhibition of apotosis of hepatocytes, immunomodulatory effects, and stimulation of bile secretion by hepatocytes and cholangiocytes. Neither accidental nor intentional overdosing with ursodeoxycholic acid has been reported. Doses of ursodeoxycholic acid in the range of 16-20 mg/kg/day have been tolerated for 6-37 months without symptoms by 7 patients. The LD50 for ursodeoxycholic acid in rats is over 5000 mg/kg given over 7-10 days and over 7500 mg/kg for mice. The most likely manifestation of severe overdose with ursodeoxycholic acid would probably be diarrhea, which should be treated symptomatically.

Ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid) is the synthetic antimicrobial agent for oral or intravenous administration. Ciprofloxacin is a member of the fluoroquinolone class of antibacterial agents. The bactericidal action of ciprofloxacin results from inhibition of the enzymes topoisomerase II (DNA gyrase) and topoisomerase IV (both Type II topoisomerases), which are required for bacterial DNA replication, transcription, repair, and recombination. Ciprofloxacin is used to treat a wide variety of infections, including infections of bones and joints, endocarditis, gastroenteritis, malignant otitis externa, respiratory tract infections, cellulitis, urinary tract infections, prostatitis, anthrax, and chancroid. In the United States, ciprofloxacin is pregnancy category C. This category includes drugs for which no adequate and well-controlled studies in human pregnancy exist, and for which animal studies have suggested the potential for harm to the fetus, but potential benefits may warrant use of the drug in pregnant women despite potential risks. Fluoroquinolones have been reported as present in a mother's milk and thus passed on to the nursing child. Oral and intravenous ciprofloxacin is approved by the FDA for use in children for only two indications due to the risk of permanent injury to the musculoskeletal system: Inhalational anthrax (postexposure) and Complicated urinary tract infections and pyelonephritis due to Escherichia coli.

Terconazole is an antifungal drug used to treat vaginal yeast infection. Terconazole may exert its antifungal activity by disrupting normal fungal cell membrane permeability. Terconazole and other triazole antifungal agents inhibit cytochrome P450 "14-alpha-demethylase" in susceptible fungi, which leads to the accumulation of lanosterol and other methylated sterols and a decrease in ergosterol concentration. Depletion of ergosterol in the membrane disrupts the structure and function of the fungal cell leading to a decrease or inhibition of fungal growth. During controlled clinical studies conducted in the United States, 521 patients with vulvovaginal candidiasis were treated with terconazole 0.4% vaginal cream. Based on comparative analyses with placebo, the adverse experiences considered most likely related to terconazole 0.4% vaginal cream were a headache and body pain. Fever and chills, vulvovaginal burning, itching, and irritation have also been reported. The adverse drug experience on terconazole most frequently causing discontinuation was vulvovaginal itching.

Amlodipine is a dihydropyridine calcium antagonist (calcium ion antagonist or slow-channel blocker) that inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. Experimental data suggest that amlodipine binds to both dihydropyridine and nondihydropyridine binding sites. The contractile processes of cardiac muscle and vascular smooth muscle are dependent upon the movement of extracellular calcium ions into these cells through specific ion channels. Amlodipine inhibits calcium ion influx across cell membranes selectively, with a greater effect on vascular mooth muscle cells than on cardiac muscle cells. Amlodipine is indicated for the treatment of hypertension and coronary artery disease.

Olsalazine is an anti-inflammatory drug used in the treatment of inflammatory bowel disease such as ulcerative colitis. Orally administered olsalazine is converted to mesalamine which is thought to be the therapeutically active agent in the treatment of ulcerative colitis. The mechanism of action of mesalamine (and sulfasalazine) is unknown but appears to be topical rather than systemic. Mucosal production of arachidonic acid (AA) metabolites, both through the cyclooxygenase pathways, i.e., prostanoids, and through the lipoxygenase pathways, i.e., leukotrienes (LTs) and hydroxyelcosatetraenoic acids (HETEs) is increased in patients with chronic inflammatory bowel disease, and it is possible that mesalamine diminishes inflammation by blocking cyclooxygenase and inhibiting prostaglandin (PG) production in the colon. After oral administration, olsalazine has limited systemic bioavailability. Based on oral and intravenous dosing studies, approximately 2.4% of a single 1.0 g oral dose is absorbed. Less than 1% of olsalazine is recovered in the urine. The remaining 98 to 99% of an oral dose will reach the colon, where each molecule is rapidly converted into two molecules of 5¬ aminosalicylic acid (5-ASA) by colonic bacteria and the low prevailing redox potential found in this environment. The liberated 5-ASA is absorbed slowly resulting in very high local concentrations in the colon. Olsalazine has been evaluated in ulcerative colitis patients in remission, as well as those with acute disease. Both sulfasalazine-tolerant and intolerant patients have been studied in controlled clinical trials. Overall, 10.4% of patients discontinued olsalazine because of an adverse experience compared with 6.7% of placebo patients. The most commonly reported adverse reactions leading to treatment withdrawal were diarrhea or loose stools (olsalazine 5.9%; placebo 4.8%), abdominal pain, and rash or itching (slightly more than 1% of patients receiving olsalazine).

Misoprostol is a prostaglandin E1 (PGE1) analogue used for the treatment and prevention of stomach ulcers. When administered, misoprostol stimulates increased secretion of the protective mucus that lines the gastrointestinal tract and increases mucosal blood flow, thereby increasing mucosal integrity. It is sometimes co-prescribed with non-steroidal anti-inflammatory drugs (NSAIDs) to prevent the occurrence of gastric ulceration, a common adverse effect of the NSAIDs. Misoprostol seems to inhibit gastric acid secretion by a direct action on the parietal cells through binding to the prostaglandin receptor. The activity of this receptor is mediated by G proteins which normally activate adenylate cyclase. The indirect inhibition of adenylate cyclase by Misoprostol may be dependent on guanosine-5’-triphosphate (GTP). The significant cytoprotective actions of misoprostol are related to several mechanisms. These include: 1. Increased secretion of bicarbonate, 2. Considerable decrease in the volume and pepsin content of the gastric secretions, 3. It prevents harmful agents from disrupting the tight junctions between the epithelial cells which stops the subsequent back diffusion of H+ ions into the gastric mucosa, 4. Increased thickness of mucus layer, 5. Enhanced mucosal blood flow as a result of direct vasodilatation, 6. Stabilization of tissue lysozymes/vascular endothelium, 7. Improvement of mucosal regeneration capacity, and 8. Replacement of prostaglandins that have been depleted as a result of various insults to the area. Misoprostol has also been shown to increase the amplitude and frequency of uterine contractions during pregnancy via selective binding to the EP-2/EP-3 prostanoid receptors. Misoprostol is indicated for the treatment of ulceration (duodenal, gastric and NSAID induced) and prophylaxis for NSAID induced ulceration. Misoprostol is also indicated for other uses that are not approved in Canada, including the medical termination of an intrauterine pregnancy used alone or in combination with methotrexate, as well as the induction of labour in a selected population of pregnant women with unfavourable cervices. This indication is avoided in women with prior uterine surgery or cesarean surgery due to an increased risk of possible uterine rupture. Misoprostol is also used for the prevention or treatment of serious postpartum hemorrhage. Misoprostol is sold under the brandname Cytotec among others.

Flurbiprofen, a propionic acid derivative, is a nonsteroidal anti-inflammatory drug that exhibits antiinflammatory, analgesic, and antipyretic activities in animal models. Flurbiprofen Tablets are indicated for relief of the signs and symptoms of rheumatoid arthritis and for relief of the signs and symptoms of osteoarthritis. It may also be used to treat pain associated with dysmenorrhea and mild to moderate pain accompanied by inflammation (e.g. bursitis, tendonitis, soft tissue trauma). Flurbiprofen may also be used topically prior to ocular surgery to prevent or reduce intraoperative miosis. Similar to other NSAIAs, the anti-inflammatory effect of flurbiprofen occurs via reversible inhibition of cyclooxygenase (COX), the enzyme responsible for the conversion of arachidonic acid to prostaglandin G2 (PGG2) and PGG2 to prostaglandin H2 (PGH2) in the prostaglandin synthesis pathway. This effectively decreases the concentration of prostaglandins involved in inflammation, pain, swelling and fever. Flurbiprofen is a non-selective COX inhibitor and inhibits the activity of both COX-1 and -2. It is also one of the most potent NSAIAs in terms of prostaglandin inhibitory activity.

Cefixime, an antibiotic, is a third-generation cephalosporin like ceftriaxone and cefotaxime. Cefixime is highly stable in the presence of beta-lactamase enzymes. As a result, many organisms resistant to penicillins and some cephalosporins due to the presence of beta-lactamases, may be susceptible to cefixime. The antibacterial effect of cefixime results from inhibition of mucopeptide synthesis in the bacterial cell wall. Like all beta-lactam antibiotics, cefixime binds to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, causing the inhibition of the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins; it is possible that cefixime interferes with an autolysin inhibitor. Cefixime is sold under the brand name Suprax, indicated for the treatment of: Uncomplicated Urinary Tract Infections Otitis Media Pharyngitis and Tonsillitis Acute Exacerbations of Chronic Bronchitis Uncomplicated Gonorrhea (cervical/urethral)

Aztreonam is the first monocyclic beta-lactam antibiotic (monobactam) originally isolated from Chromobacterium violaceum. Aztreonam has a high affinity for the protein-binding protein 3 (PBP-3) of aerobic gram-negative bacteria. Most of these organisms are inhibited and killed at low concentrations of the drug. Aztreonam must be administered as an intravenous or intramuscular injection (AZACTAM®), or inhaled (CAYSTON®). Aztreonam for injection is indicated for the treatment of the following infections caused by susceptible gram-negative microorganisms: urinary tract, lower respiratory tract, skin and skin-structure, intra-abdominal and gynecologic infections as well as for septicemia. Aztreonam for inhalation solution is indicated to improve respiratory symptoms in cystic fibrosis patients with Pseudomonas aeruginosa.