Quetiapine, marketed as SEROQUEL XR, is an atypical antipsychotic approved for the treatment of schizophrenia, bipolar disorder, and along with an antidepressant to treat major depressive disorder. The mechanism of action of SEROQUEL XR in the treatment of schizophrenia, bipolar disorder and major depressive disorder (MDD), is unknown. However, its efficacy in schizophrenia could be mediated through a combination of dopamine type 2 (D2) and serotonin type 2A (5HT2A) antagonism. The active metabolite, N-desalkyl quetiapine (norquetiapine), has similar activity at D2, but greater activity at 5HT2A receptors, than the parent drug (quetiapine). Quetiapine’s efficacy in bipolar depression and MDD may partly be explained by the high affinity and potent inhibitory effects that norquetiapine exhibits for the norepinephrine transporter. Antagonism at receptors other than dopamine and serotonin with similar or greater affinities may explain some of the other effects of quetiapine and norquetiapine: antagonism at histamine H1 receptors may explain the somnolence, antagonism at adrenergic α1b receptors may explain the orthostatic hypotension, and antagonism at muscarinic M1 receptors may explain the anticholinergic effects. Quetiapine and norquetiapine have affinity for multiple neurotransmitter receptors including dopamine D1 and D2, serotonin 5HT1A and 5HT2A, histamine H1, muscarinic M1, and adrenergic α1b and α2 receptors. Quetiapine differs from norquetiapine in having no appreciable affinity for muscarinic M1 receptors whereas norquetiapine has high affinity. Quetiapine and norquetiapine lack appreciable affinity for benzodiazepine receptors.

Olanzapine is a novel antipsychotic agent marketed by Lilly & Co. It has a pleotrophic pharmacology and affects dopaminergic, serotonergic, muscarinic and adrenergic activities. Olanzapine is used to treat the symptoms of psychotic conditions such as schizophrenia and bipolar disorder (manic depression) in adults and children who are at least 13 years old. Olanzapine is sometimes used together with other antipsychotic medications or antidepressants. The mechanism of action of olanzapine, as with other drugs having efficacy in schizophrenia, is unknown. However, it has been proposed that this drug’s efficacy in schizophrenia is mediated through a combination of dopamine and serotonin type 2 (5HT2) antagonism. The mechanism of action of olanzapine in the treatment of acute manic or mixed episodes associated with bipolar I disorder is unknown. Olanzapine treatment led to rapid phosphorylation of kinases from all three pathways in PC12 cells. Phosphorylation of Akt was blocked with selective inhibitors (wortmannin and LY294002), which implicates phosphoinositide 3-kinase (PI3K) in the signaling cascade. Short-term mitogenic effects of olanzapine were abolished with a selective inhibitor of Akt, but not by inhibition of the ERK pathway. Olanzapine is metabolized by the cytochrome P450 system; principally by isozyme 1A2 and to a lesser extent by 2D6. By these mechanisms more than 40% of the oral dose, on average, is removed by the hepatic first-pass effect. Drugs or agents that increase the activity of CYP1A2, notably tobacco smoke, may significantly increase hepatic first-pass clearance of Olanzapine; conversely, drugs which inhibit 1A2 activity (examples: Ciprofloxacin, Fluvoxamine) may reduce Olanzapine clearance. The most common side effects appear to be somnolence and weight gain. About 11% of patients gain weight -especially if on a high starting dose and if they were underweight pre-treatment. Sexual dysfunction is a problem for many patients, although sexual dysfunction in schizophrneia does not appear to be primarily attributable to drugs.

Atovaquone is a chemical compound that belongs to the class of naphthoquinones; it is manufactured in the US in the liquid form, or oral suspension, under the brand name Mepron. Meron is used for the treatment or prevention of Pneumocystis carinii pneumonia in patients who are intolerant to trimethoprim-sulfamethoxazole (TMP-SMX). Also indicated for the acute oral treatment of mild to moderate PCP in patients who are intolerant to TMP-SMX. The mechanism of action against Pneumocystis jiroveci has not been fully elucidated. In Plasmodium species, the site of action appears to be the cytochrome bc1 complex (Complex III). Several metabolic enzymes are linked to the mitochondrial electron transport chain via ubiquinone. Inhibition of electron transport by atovaquone results in indirect inhibition of these enzymes. The ultimate metabolic effects of such blockade may include inhibition of nucleic acid and adenosine triphosphate (ATP) synthesis. Several laboratories, using different in vitro methodologies, have shown the IC50 (50% inhibitory concentration) of atovaquone against P. jiroveci to be 0.1 to 3.0 mcg/mL.

Desoximetasone (Topicort®) is a topical anti-inflammatory glucocorticoid indicated for the relief of the inflammatory and pruritic manifestations of corticosteroid-responsive dermatoses and for the treatment of plaque psoriasis in patients 18 years of age or older. The topical corticosteroids constitute a class of primarily synthetic steroids used as anti-inflammatory and antipruritic agents. They play a role in cellular signaling, immune function, inflammation and protein regulation; however, the precise mechanism of action in psoriasis is unknown. The mechanism of anti-inflammatory activity of the topical corticosteroids is also unclear. Various laboratory methods, including vasoconstrictor assays, are used to compare and predict potencies and/or clinical efficacies of the topical corticosteroids. There is some evidence to suggest that a recognizable correlation exists between vasoconstrictor potency and therapeutic efficacy in man.

Alatrofloxacin is a fluoroquinolone antibiotic developed as a mesylate salt and was sold under brand name Trovan, but was withdrawn from the U.S. market in 2001. Trovan was indicated for the treatment of patients initiating therapy in in-patient health care facilities (i.e., hospitals and long term nursing care facilities) with serious, life- or limb-threatening infections caused by susceptible strains of the designated microorganisms in the conditions listed below. Nosocomial pneumonia caused by Escherichia coli, Pseudomonas aeruginosa, Haemophilus influenzae, or Staphylococcus aureus. Community acquired pneumonia caused by Streptococcus pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae, Staphylococcus aureus. Complicated intra-abdominal infections, including post-surgical infections caused by Escherichia coli. Gynecologic and pelvic infections including endomyometritis, parametritis, septic abortion and post-partum infections caused by Escherichia coli, Bacteroides fragilis, viridans group streptococci, Enterococcus faecalis. Complicated skin and skin structure infections, including diabetic foot infections, caused by Staphylococcus aureus, Streptococcus agalactiae, Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli, or Proteus mirabilis. After intravenous administration, alatrofloxacin is rapidly converted to trovafloxacin, which is responsible for therapeutic effect. Plasma concentrations of alatrofloxacin are below quantifiable levels within 5 to 10 minutes of completion of a 1 hour infusion.

Acrivastine is a triprolidine analog antihistamine indicated for the treatment of allergies and hay fever. As an H1 receptor antagonist, it functions by blocking the action of histamine at this receptor thereby preventing the symptoms associated with histamine release such as pruritis, vasodilation, hypotension, edema, bronchoconstriction, and tachycardia. Acrivastine is currently available in combination with pseudoephedrine as the FDA-approved product Semprex-D. It’s used for the relief of symptoms associated with seasonal allergic rhinitis such as sneezing, rhinorrhea, pruritus, lacrimation, and nasal congestion. Acrivastine, a structural analog of triprolidine hydrochloride, exhibits H1-antihistaminic activity in isolated tissues, animals, and humans, and has sedative effects in humans. The propionic acid derivative of acrivastine is a metabolite in several animal species (as well as in man) and also exhibits H1-antihistaminic activity.

BEPHENIUM HYDROXYNAPHTHOATE is an anthelmintic agent used in the treatment of hookworm and roundworm infections (Ancylostoma duodenale, Ascaris lumbricoides, and Necatore americanus). It targets the AChRs of nematodes producing spastic paralysis of the worms.

Ethinamate was used to treat insomnia (trouble in sleeping) under the brand name VALMID, but then was replaced by other more efficacy medicines. The mechanism of action was not known. However, was studies, which showed that ethinamate inhibits carbonic anhydrases I and did not inhibit II. Nevertheless, even inhibition carbonic anhydrases I is not sufficiently strong to implicate carbonic anhydrases I in the mechanism of action.