Oxcarbazepine and its active metabolite (10,11-dihydro-10-hydroxy-carbazepine, MHD) have been effective in animal models of epilepsy that generally predict efficacy in generalized tonic-clonic seizures and partial seizures in humans. The pharmacokinetic profile of oxcarbazepine is less complicated than that of carbamazepine, with less metabolism by the cytochrome P450 system, no production of an epoxide metabolite, and lower plasma protein binding. The clinical efficacy and tolerability of oxcarbazepine have been demonstrated in trials in adults, children, and the elderly. The pharmacological activity of oxcarbazepine is primarily exerted through the 10-monohydroxy metabolite (MHD) of oxcarbazepine. The precise mechanism by which oxcarbazepine and MHD exert their antiseizure effect is unknown; however, in vitro electrophysiological studies indicate that they produce blockade of voltage-sensitive sodium channels, resulting in stabilization of hyperexcited neural membranes, inhibition of repetitive neuronal firing, and diminution of propagation of synaptic impulses. These actions are thought to be important in the prevention of seizure spread in the intact brain. In addition, increased potassium conductance and modulation of high-voltage activated calcium channels may contribute to the anticonvulsant effects of the drug.

Quinupristin is an antibiotic compound and a semisynthetic derivative of pristinamycin Ia. Quinupristin is a combination of three peptide macrolactones. Quinupristin is used in combination with dalfopristin, another antibiotic, under the trade name Synercid. Synercid is indicated for treatment of complicated skin and skin structure infections caused by methicillin-susceptible Staphylococcus aureus or Streptococcus pyogenes. The mechanism of action of quinupristin is inhibition of the late phase of protein synthesis in the bacterial ribosome. Quinupristin binds to 23S rRNA within the 50S ribosomal subunit and prevents elongation of the polypeptide as well as causing incomplete chains to be released. Adverse reactions to Synercid include inflammation at infusion site, rash, nausea, vomiting and others.

Dalfopristin is a pristinamycin-like component of anti-bacterial drug called Synercid which also containes quinupristin (quinupristin:dalfopristin ratio is 30:70 (w/w)). The drug was approved by FDA and used for the treatment of skin diseases caused by Staphylococcus aureus or Streptococcus pyogenes. Dalfopristin binds to the RNA of the 50S ribosomal subunit and thus inhibits the late phase of protein synthesis.

Tolcapone is a potent, selective, and reversible inhibitor of catechol-O-methyltransferase (COMT). In humans, COMT is distributed throughout various organs. COMT catalyzes the transfer of the methyl group of S-adenosyl-L-methionine to the phenolic group of substrates that contain a catechol structure. Physiological substrates of COMT include dopa, catecholamines (dopamine, norepinephrine, epinephrine) and their hydroxylated metabolites. The function of COMT is the elimination of biologically active catechols and some other hydroxylated metabolites. COMT is responsible for the elimination of biologically active catechols and some other hydroxylated metabolites. In the presence of a decarboxylase inhibitor, COMT becomes the major metabolizing enzyme for levodopa catalyzing it to 3-methoxy-4-hydroxy-L-phenylalanine (3-OMD) in the brain and periphery. When tolcapone is given in conjunction with levodopa and an aromatic amino acid decarboxylase inhibitor, such as carbidopa, plasma levels of levodopa are more sustained than after administration of levodopa and an aromatic amino acid decarboxylase inhibitor alone. It is believed that these sustained plasma levels of levodopa result in more constant dopaminergic stimulation in the brain, leading to greater effects on the signs and symptoms of Parkinson's disease in patients as well as increased levodopa adverse effects, sometimes requiring a decrease in the dose of levodopa. The precise mechanism of action of tolcapone is unknown, but it is believed to be related to its ability to inhibit COMT and alter the plasma pharmacokinetics of levodopa, resulting in an increase in plasma levodopa concentrations. The inhibition of COMT also causes a reduction in circulating 3-OMD as a result of decreased peripheral metabolism of levodopa. This may lead to an increase distribution of levodopa into the CNS through the reduction of its competitive substrate, 3-OMD, for transport mechanisms. Sustained levodopa concentrations presumably result in more consistent dopaminergic stimulation, resulting in greater reduction in the manifestations of parkinsonian syndrome. Tolcapone is used as an adjunct to levodopa/carbidopa therapy for the symptomatic treatment of Parkinson's Disease. This drug is generally reserved for patients with parkinsonian syndrome receiving levodopa/carbidopa who are experiencing symptom fluctuations and are not responding adequately to or are not candidates for other adjunctive therapies. Tolcapone is sold under the brand name Tasmar.

Clopidogrel, an antiplatelet agent structurally and pharmacologically similar to ticlopidine, is used to inhibit blood clots in a variety of conditions such as peripheral vascular disease, coronary artery disease, and cerebrovascular disease. Clopidogrel is sold under the name Plavix by Sanofi and Bristol-Myers Squibb. Plavix (clopidogrel bisulfate) is an inhibitor of ADP-induced platelet aggregation acting by direct inhibition of adenosine diphosphate (ADP) binding to its receptor and of the subsequent ADPmediated activation of the glycoprotein GPIIb/IIIa complex. Clopidogrel must be metabolized by CYP450 enzymes to produce the active metabolite that inhibits platelet aggregation. The active metabolite of clopidogrel selectively inhibits the binding of adenosine diphosphate (ADP) to its platelet P2Y12 receptor and the subsequent ADPmediated activation of the glycoprotein GPIIb/IIIa complex, thereby inhibiting platelet aggregation. This action is irreversible. Consequently, platelets exposed to clopidogrel’s active metabolite are affected for the remainder of their lifespan (about 7 to 10 days). Platelet aggregation induced by agonists other than ADP is also inhibited by blocking the amplification of platelet activation by released ADP. Plavix (clopidogrel bisulfate) is indicated for the reduction of atherothrombotic events.

Moxidectin is a semi-synthetic methoxime derivative of LL F-2924α, commonly referred as F-alpha or nemadectin F-alpha is a product of fermentation of Streptomyces cyaneogriseus subsp. noncyanogenus, a bacterial organism isolated in 1983 from a sample of sand from Victoria, Australia. Moxidectin is a potent, broad-spectrum endectocide with activity against a wide range of nematodes, insects and acari. The compound acts by binding to ligand-gated chloride channels, more specifically the subtypes that are gamma-aminobutyric (GABA) mediated and glutamate-gated. The consequence of Moxidectin binding and activation is an increased permeability, leading to an influx of chloride ions and flaccid paralysis of the parasite leading to death. The macrocyclic lactones probably act by binding to and opening glutamate-gated chloride channels found only in neurons and myocytes of invertebrates. Because moxidectin is very lipophilic, it becomes highly concentrated in the serum. When the concentration of moxidectin in the serum is high, moxidectin is able to cross the blood-brain barrier. Once it is in the central nervous system, a macrocyclic lactone stimulates the synaptic secretion of the inhibitory neurotransmitter, GABA. By binding at the receptor site, GABA causes influx of chloride ions into neurons, causing the neurons to become hyperpolarised, which in turn, causes diminution in neuronal activity, resulting in sedation and relaxation of the skeletal muscles. Signs displayed by foals with moxidectin toxicity included dyspnoea, depression, ataxia, weakness, coma and seizures. In a Phase 3 study compared the efficacy, safety and tolerability of moxidectin and ivermectin in subjects infected with Onchocerca volvulus, which is the parasite that causes river blindness.

Ropinirole (INN; trade names Requip, Repreve, Ronirol, Adartrel) is a dopamine agonist of the non-ergoline class of medications, used in the treatment of Parkinson's disease and restless legs syndrome. Although the precise mechanism of action of ropinirole as a treatment for Parkinson's disease is unknown, it is believed to be related to its ability to stimulate dopamine receptors in the striatum. This conclusion is supported by electrophysiologic studies in animals that have demonstrated that ropinirole influences striatal neuronal firing rates via activation of dopamine receptors in the striatum and the substantia nigra, the site of neurons that send projections to the striatum. Ropinirole is a nonergot dopamine agonist with high relative in vitro specificity and full intrinsic activity at the D2 subfamily of dopamine receptors, binding with higher affinity to D3 than to D2 or D4 receptor subtypes. The relevance of D3 receptor binding in Parkinson's disease is unknown. The mechanism of ropinirole-induced postural hypotension is presumed to be due to a D2 -mediated blunting of the noradrenergic response to standing and subsequent decrease in peripheral vascular resistance. Ropinirole can cause nausea, dizziness, hallucinations, orthostatic hypotension, and sudden sleep attacks during the daytime. Unusual side effects specific to D3 agonists such as ropinirole and pramipexole can include hypersexuality, punding, and compulsive gambling, even in patients without a history of these behaviors.

Irbesartan is an angiotensin receptor blocker (ARB) used mainly for the treatment of hypertension. It was developed by Sanofi Research (now part of Sanofi-Aventis). It is marketed under the trade names Aprovel, Karvea, and Avapro. AVAPRO is an angiotensin II receptor blocker (ARB) indicated for: • Treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. • Treatment of diabetic nephropathy in hypertensive patients with type 2 diabetes, an elevated serum creatinine, and proteinuria. Irbesartan is a specific competitive antagonist of AT1 receptors with a much greater affinity (more than 8500-fold) for the AT1 receptor than for the AT2 receptor and no agonist activity.

Letrozole (trade name Femara), a nonsteroidal aromatase inhibitor. Femara is indicated for the adjuvant treatment of postmenopausal women with hormone receptor positive early breast cancer. Also is indicated for the extended adjuvant treatment of early breast cancer in postmenopausal women, who have received 5 years of adjuvant tamoxifen therapy. Femara has to be used for first-line treatment of postmenopausal women with hormone receptor positive or unknown, locally advanced or metastatic breast cancer and for the treatment of advanced breast cancer in postmenopausal women with disease progression following antiestrogen therapy. Treatment of breast cancer thought to be hormonally responsive (i.e., estrogen and/or progesterone receptor positive or receptor unknown) has included a variety of efforts to decrease estrogen levels (ovariectomy, adrenalectomy, hypophysectomy) or inhibit estrogen effects (antiestrogens and progestational agents). These interventions lead to decreased tumor mass or delayed progression of tumor growth in some women. In postmenopausal women, estrogens are mainly derived from the action of the aromatase enzyme, which converts adrenal androgens (primarily androstenedione and testosterone) to estrone and estradiol. The suppression of estrogen biosynthesis in peripheral tissues and in the cancer tissue itself can therefore be achieved by specifically inhibiting the aromatase enzyme. Letrozole inhibits the conversion of androgens to estrogens. Letrozole selectively inhibits gonadal steroidogenesis but has no significant effect on adrenal mineralocorticoid or glucocorticoid synthesis. Letrozole inhibits the aromatase enzyme by competitively binding to the heme of the cytochrome P450 subunit of the enzyme, resulting in a reduction of estrogen biosynthesis in all tissues. Treatment of women with letrozole significantly lowers serum estrone, estradiol and estrone sulfate and has not been shown to significantly affect adrenal corticosteroid synthesis, aldosterone synthesis, or synthesis of thyroid hormones. Letrozole is rapidly and completely absorbed from the gastrointestinal tract and absorption is not affected by food. Metabolism to a pharmacologically inactive carbinol metabolite (4,4'¬ methanol-bisbenzonitrile) and renal excretion of the glucuronide conjugate of this metabolite is the major pathway of letrozole clearance. In human microsomes with specific CYP isozyme activity, CYP3A4 metabolized letrozole to the carbinol metabolite while CYP2A6 formed both this metabolite and its ketone analog. In human liver microsomes, letrozole strongly inhibited CYP2A6 and moderately inhibited CYP2C19. The most common side effects are sweating, hot flashes, arthralgia (joint pain), and fatigue

Bromfenac is a topical, nonsteroidal anti-inflammatory drug (NSAID) for ophthalmic use. It is indicated for the treatment of postoperative inflammation and reduction of ocular pain in patients who have undergone cataract surgery. The mechanism of its action is thought to be due to its ability to block prostaglandin synthesis by inhibiting cyclooxygenase 1 and 2. The most commonly reported adverse reactions in 3 to 8% of patients were anterior chamber inflammation, foreign body sensation, eye pain, photophobia and vision blurred.