Dextromilnacipran (1R, 2S/F2696) is an enantiomer of milnacipran, a serotonin/norepinephrine (5-HT/NE) reuptake inhibitor. Dextromilnacipran is pharmacologically less active as compared with racemic mixture and levomilnacipran (1S, 2R/F2695).

Sitagliptin (MK-0431), chemically (2R)-4-Oxo-4-[3- (trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl]-1-(2,4,5-trifl uorophenyl)butan-2-amine has a very high selectivity towards DPP-4, with an IC(50) of 18 nM. There is no affinity towards other DDP enzymes (DPP- 8 and DPP-9). It has been approved for the treatment of type 2 diabetes in the USA and Europe and is registered by the name Januvia (Merck Pharmaceuticals, Whitehouse Station, NJ, USA). In healthy volunteers and in patients with type 2 diabetes of different ethnic background, the tolerability of different doses given once or twice daily is good. The drug works to competitively inhibit a protein/enzyme, dipeptidyl peptidase 4 (DPP-4), that results in an increased amount of active incretins (GLP-1 and GIP), reduced amount of release of glucagon (diminishes its release) and increased release of insulin. Sitagliptin is an incretin enhancer and the first marketed medication belonging to the gliptin class. In fact, no published literature exists regarding incidence or severity of hypoglycemia when sitagliptin is used off-label in combined with insulin therapy. However, is recommended to use methods to avoid hypoglycemia when using this off-label combination. Approximately 79% of sitagliptin is excreted unchanged in the urine with metabolism being a minor pathway of elimination. Elimination of sitagliptin occurs primarily via renal excretion and involves active tubular secretion. Sitagliptin is a substrate for human organic anion transporter-3 (hOAT-3), which may be involved in the renal elimination of sitagliptin

Pemetrexed is a new-generation antifolate, approved for the treatment of mesothelioma and non-small cell lung cancer, currently being evaluated for the treatment of a variety of other solid tumors. Pemetrexed, is a folate analog metabolic inhibitor that exerts its action by disrupting folate-dependent metabolic processes essential for cell replication. In vitro studies have shown that pemetrexed inhibits thymidylate synthase (TS), dihydrofolate reductase (DHFR), glycinamide ribonucleotide formyltransferase (GARFT) and and to a lesser extent aminoimidazole carboxamide ribonucleotide formyltransferase (AICARFT), which are folate-dependent enzymes involved in the de novo biosynthesis of thymidine and purine nucleotides. Pemetrexed is taken into cells by membrane carriers such as the reduced folate carrier and membrane folate binding protein transport systems. Once in the cell, pemetrexed is converted to polyglutamate forms by the enzyme folylpolyglutamate synthetase. The polyglutamate forms are retained in cells and are inhibitors of TS and GARFT. Polyglutamation is a time- and concentration-dependent process that occurs in tumor cells and, is thought to occur to a lesser extent, in normal tissues. Polyglutamated metabolites are thought to have an increased intracellular half-life resulting in prolonged drug action in malignant cells.

Pregabalin, marketed under the brand name Lyrica among others. LYRICA is indicated for: Neuropathic pain associated with diabetic peripheral neuropathy (DPN) Postherpetic neuralgia (PHN); Adjunctive therapy for adult patients with partial onset seizures; Fibromyalgia; Neuropathic pain associated with spinal cord injury. It has been shown the clinical effects of pregabalin are likely due to direct and selective interactions with α(2)δ-1 and α(2)δ-2 subunits of voltage-gated calcium channels. While pregabalin is a structural derivative of the inhibitory neurotransmitter gamma aminobutyric acid (GABA), it does not bind directly to GABAA, GABAB, or benzodiazepine receptors, does not augment GABAA responses in cultured neurons, does not alter rat brain GABA concentration or have acute effects on GABA uptake or degradation. However, in cultured neurons prolonged application of pregabalin increases the density of GABA transporter protein and increases the rate of functional GABA transport. Pregabalin does not block sodium channels, is not active at opiate receptors, and does not alter cyclooxygenase enzyme activity. It is inactive at serotonin and dopamine receptors and does not inhibit dopamine, serotonin, or noradrenaline reuptake.

Ertapenem is a carbapenem antibiotic marketed by Merck as Invanz. The bactericidal activity of ertapenem results from the inhibition of cell wall synthesis and is mediated through ertapenem binding to penicillin binding proteins (PBPs). In Escherichia coli, it has strong affinity toward PBPs 1a, 1b, 2, 3, 4 and 5 with preference for PBPs 2 and 3. Ertapenem has been designed to be effective against Gram-negative and Gram-positive bacteria. The most common drug-related adverse experiences in patients treated with INVANZ, including those who were switched to therapy with an oral antimicrobial, were diarrhea (5.5%), infused vein complication (3.7%), nausea (3.1%), headache (2.2%), vaginitis in females (2.1%), phlebitis/thrombophlebitis (1.3%), and vomiting (1.1%). The coadministration with probenecid to extend the half-life of ertapenem is not recommended.

Frovatriptan succinate (trade name Frova) is a selective 5-hydroxytryptamine1 (5-HT1B/1D) receptor subtype agonist, and is used for the treatment of migraine attacks with or without aura in adults. Frovatriptan has no significant effects on GABAA mediated channel activity and has no significant affinity for benzodiazepine binding sites. Frovatriptan is believed to act on extracerebral, intracranial arteries and to inhibit excessive dilation of these vessels in migraine. Serious but rare cardiac events have been reported in patients with risk factors predictive of coronary artery disease (CAD). These include coronary artery vasospasm, transient myocardial ischemia, myocardial infarction, ventricular tachycardia and ventricular fibrillation.

Dexmethylphenidate is the dextrorotary form of methylphenidate. Dexmethylphenidate is marketed under the trade name Focalin. Focalin (dexmethylphenidate hydrochloride) is the d-threo-enantiomer of racemic methylphenidate hydrochloride, which is a 50/50 mixture of the d-threo and l-threoenantiomers. Focalin is a central nervous system (CNS) stimulant, available in three tablet strengths. Each tablet contains dexmethylphenidate hydrochloride 2.5, 5, or 10 mg for oral administration. Dexmethylphenidate is used as a treatment for ADHD, ideally in conjunction with psychological, educational, behavioral or other forms of treatment. Methylphenidate blocks dopamine uptake in central adrenergic neurons by blocking dopamine transport or carrier proteins. Methylphenidate acts at the brain stem arousal system and the cerebral cortex and causes increased sympathomimetic activity in the central nervous system. Methylphenidate is a catecholamine reuptake inhibitor that indirectly increases catecholaminergic neurotransmission by inhibiting the dopamine transporter (DAT) and norepinephrine transporter (NET), which are responsible for clearing catecholamines from the synapse, particularly in the striatum and meso-limbic system.

Amprenavir is an inhibitor of HIV-1 protease. Amprenavir binds to the active site of HIV-1 protease and thereby prevents the processing of viral gag and gag-pol polyprotein precursors, resulting in the formation of immature non-infectious viral particles. Amprenavir-containing combination regimens have shown virological efficacy, and have generally been well tolerated, in patients with HIV infection (primarily treatment-naive or protease inhibitor-naive). Fosamprenavir (GW433908, Lexiva, Telzir) is an oral prodrug of amprenavir, with a reduced daily pill burden. The use of protease inhibitors has also been associated with dyslipidemia and an increased risk of cardiovascular disease. Amprenavir activates Pregnane X receptor to mediate dyslipidemia.

Tamsulosin, a sulfamoylphenethylamine-derivative alpha-adrenoceptor blocker with enhanced specificity for the alpha-adrenoceptors of the prostate, is commonly used to treat benign prostatic hyperplasia (BPH). The drug is commercially available in a racemic mixture of 2 isomers, and is pharmacologically related to doxazocin, prazosin, and terazosin. However, unlike these drugs, tamsulosin has a higher affinity for the alpha-1A- adrenergic receptors, which are located in vascular smooth muscle. Studies show that tamsulosin has about 12 times greater affinity for alpha-1 adrenergic receptors in the prostate than those in the aorta, which may result in a reduced incidence of adverse cardiovascular effects. Tamsulosin is sold under the trade name Flomax.

Fenoldopam (marketed under the brand name Corlopam) is a drug and synthetic benzazepine derivative which acts as a selective D1 receptor partial agonist. Fenoldopam is a rapid-acting vasodilator. It is an agonist for D1-like dopamine receptors and binds with moderate affinity to α2-adrenoceptors. It has no significant affinity for D2-like receptors, α1 and β adrenoceptors, 5HT1 and 5HT2 receptors, or muscarinic receptors. Fenoldopam is a racemic mixture with the R-isomer responsible for the biological activity. The R-isomer has approximately 250-fold higher affinity for D1-like receptors than does the S-isomer. Fenoldopam Mesylate Injection, USP is indicated for the in-hospital, short-term (up to 48 hours) management of severe hypertension when rapid, but quickly reversible, emergency reduction of blood pressure is clinically indicated, including malignant hypertension with deteriorating end-organ function.