Felodipine is a long-acting 1,4-dihydropyridine calcium channel blocker (CCB)b. It acts primarily on vascular smooth muscle cells by stabilizing voltage-gated L-type calcium channels in their inactive conformation. By inhibiting the influx of calcium in smooth muscle cells, felodipine prevents calcium-dependent myocyte contraction and vasoconstriction. Felodipine is the most potent CCB in use and is unique in that it exhibits fluorescent activity. In addition to binding to L-type calcium channels, felodipine binds to a number of calcium-binding proteins, exhibits competitive antagonism of the mineralcorticoid receptor, inhibits the activity of calmodulin-dependent cyclic nucleotide phosphodiesterase, and blocks calcium influx through voltage-gated T-type calcium channels. Felodipine is used to treat mild to moderate essential hypertension.

Fludarabine or fludarabine phosphate is a chemotherapy drug used in the treatment of hematological malignancies (cancers of blood cells such as leukemias and lymphomas). It is a purine analog, which interferes with DNA synthesis. Fludarabine phosphate is a fluorinated nucleotide analog of the antiviral agent vidarabine, 9-β-D-arabinofuranosyladenine (ara-A), that is relatively resistant to deamination by adenosine deaminase. Fludarabine (marketed as fludarabine phosphate under the trade name Fludara) is a chemotherapy drug used in the treatment of hematological malignancies. Fludarabine phosphate is rapidly dephosphorylated to 2-fluoro-ara-A and then phosphorylated intracellularly by deoxycytidine kinase to the active triphosphate, 2-fluoro-ara-ATP. This metabolite appears to act by inhibiting DNA polymerase alpha, ribonucleotide reductase and DNA primase, thus inhibiting DNA synthesis. The mechanism of action of this antimetabolite is not completely characterized and may be multi-faceted.

Azithromycin is one of the world's best-selling antibiotics, used to treat or prevent certain bacterial infections: Acute bacterial exacerbations of chronic bronchitis in adults; acute bacterial sinusitis in adults; uncomplicated skin and skin structure infections in adults; urethritis and cervicitis in adults; genital ulcer disease in men; acute otitis media in pediatric patients; community-acquired pneumonia in adults and pediatric patients; pharyngitis/tonsillitis in adults and pediatric patients. Azithromycin should not be used in patients with pneumonia who are judged inappropriate for oral therapy because of moderate to severe illness or risk factors. A team of researchers at the Croatian pharmaceutical company Pliva, discovered azithromycin in 1980. It was patented in 1981. In 1986, Pliva and Pfizer signed a licensing agreement, which gave Pfizer exclusive rights for the sale of azithromycin in Western Europe and the United States. Pliva put its azithromycin on the market in Central and Eastern Europe under the brand name of Sumamed in 1988. Pfizer launched azithromycin under Pliva's license in other markets under the brand name Zithromax in 1991. Azithromycin is a semi-synthetic macrolide antibiotic of the azalide class. Like other macrolide antibiotics, azithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit of the bacterial 70S ribosome. Binding inhibits peptidyl transferase activity and interferes with amino acid translocation during the process of translation. Its effects may be bacteriostatic or bactericidal depending of the organism and the drug concentration. Its long half-life, which enables once daily dosing and shorter administration durations, is a property distinct from other macrolides.

Fumazenil is an imidazobenzodiazepine derivative and a potent benzodiazepine receptor antagonist that competitively inhibits the activity at the benzodiazepine recognition site on the GABA/benzodiazepine receptor complex, thereby reversing the effects of benzodiazepine on the central nervous system. Fumazenil is used for the complete or partial reversal of the sedative effects of benzodiazepines in cases where general anesthesia has been induced and/or maintained with benzodiazepines, and where sedation has been produced with benzodiazepines for diagnostic and therapeutic procedures. Also for the management of benzodiazepine overdose as an adjunct for appropriate supportive and symptomatic measures. Flumazenil went off patent in 2008 so at present generic formulations of this drug are available.

Fluticasone propionate, a medium-potency synthetic corticosteroid, is used topically to relieve inflammatory and pruritic symptoms of dermatoses and psoriasis, intranasally to manage symptoms of allergic and non-allergic rhinitis, and orally for the treatment of asthma. Fluticasone proprionate is marketed under several different brand names such as Flonase®. Fluticasone propionate is also available as a combination product of azelastine hydrochloride and fluticasone propionate called Dymista™. Dymista™ is indicated in patients over 12 years old for symptomatic relief of seasonal allergic rhinitis. Fluticasone propionate binds to the glucocorticoid receptor. Unbound corticosteroids cross the membranes of cells such as mast cells and eosinophils, binding with high affinity to glucocorticoid receptors (GR). The results include alteration of transcription and protein synthesis, a decreased release of leukocytic acid hydrolases, reduction in fibroblast proliferation, prevention of macrophage accumulation at inflamed sites, reduction of collagen deposition, interference with leukocyte adhesion to the capillary wall, reduction of capillary membrane permeability and subsequent edema, reduction of complement components, inhibition of histamine and kinin release, and interference with the formation of scar tissue. In the management of asthma, the glucocorticoid receptor complexes down-regulates proinflammatory mediators such as interleukin-(IL)-1, 3, and 5, and up-regulates anti-inflammatory mediators such as IkappaB [inhibitory molecule for nuclear factor kappaB1], IL-10, and IL-12. The antiinflammatory actions of corticosteroids are also thought to involve inhibition of cytosolic phospholipase A2 (through activation of lipocortin-1 (annexin)) which controls the biosynthesis of potent mediators of inflammation such as prostaglandins and leukotrienes.

Mefloquine, sold under the brand names Lariam among others, is a medication used to for the treatment of mild to moderate acute malaria caused by Mefloquineuine-susceptible strains of Plasmodium falciparum (both chloroquine-susceptible and resistant strains) or by Plasmodium vivax. Also for the prophylaxis of Plasmodium falciparum and Plasmodium vivax malaria infections, including prophylaxis of chloroquine-resistant strains of Plasmodium falciparum. Mefloquine acts as a blood schizonticide. Mefloquine is active against the erythrocytic stages of Plasmodium species. However, the drug has no effect against the exoerythrocytic (hepatic) stages of the parasite. Mefloquine is effective against malaria parasites resistant to chloroquine. Mefloquine is a chiral molecule. According to some research, the (+) enantiomer is more effective in treating malaria, and the (-) enantiomer specifically binds to adenosine receptors in the central nervous system, which may explain some of its psychotropic effects.

Ganciclovir is a synthetic acyclic nucleoside analogue of 2'-deoxyguanosine active against cytomegalovirus. Ganciclovir has been shown to be active against cytomegalovirus (CMV) and herpes simplex virus (HSV) in humans. To achieve anti-CMV activity, ganciclovir is phosphorylated first to the monophosphate form by a CMV-encoded (UL97 gene) protein kinase homologue, then to the di- and triphosphate forms by cellular kinases. Ganciclovir triphosphate concentrations may be 100-fold greater in CMV-infected than in uninfected cells, indicating preferential phosphorylation in infected cells. Ganciclovir triphosphate, once formed, persists for days in the CMV-infected cell. Ganciclovir triphosphate is believed to inhibit viral DNA synthesis by (1) competitive inhibition of viral DNA polymerases; and (2) incorporation into viral DNA, resulting in eventual termination of viral DNA elongation. Ganciclovir is indicated for the treatment of CMV retinitis in immunocompromised patients, including patients with acquired immunodeficiency syndrome (AIDS) and for the treatment of acute herpetic keratitis.

Propafenone (brand name Rythmol SR or Rytmonorm) is a class 1C anti-arrhythmic medication, which treats illnesses associated with rapid heartbeats such as atrial and ventricular arrhythmias. The electrophysiological effect of propafenone manifests itself in a reduction of upstroke velocity (Phase 0) of the monophasic action potential. In Purkinje fibers, and to a lesser extent myocardial fibers, propafenone reduces the fast inward current carried by sodium ions, which is responsible for the drugs antiarrhythmic actions. Diastolic excitability threshold is increased and effective refractory period prolonged. Propafenone reduces spontaneous automaticity and depresses triggered activity. At very high concentrations in vitro, propafenone can inhibit the slow inward current carried by calcium but this calcium antagonist effect probably does not contribute to antiarrhythmic efficacy. Propafenone is metabolized primarily in the liver. Because of its short half-life, it requires dosing two or three times daily to maintain steady blood levels. The long-term safety of propafenone is unknown. Because it is structurally similar to another anti-arrhythmic medicine, flecainide, similar cautions should be exercised in its use. Flecainide and propafenone, like other antiarrhythmic drugs, have been shown to increase the occurrence of arrhythmias (5.3% for propafenone, Teva physician prescribing information), primarily in patients with underlying heart disease. However, their use in structurally normal hearts is considered safe.

Clozapine was discovered in 1958 by an anesthetist and now it is used for the treatment of schizophrenia. Although the exact mechanism of its action is unknown, the effect of clozapine on schizophrenia is associated with inhibition of dopamine D2 and serotonin 2A receptors.

Selegiline, also known as L-deprenyl, is a substituted phenethylamine, a selective, irreversible inhibitor of Type B monoamine oxidase. Selegiline is available in pill form under many brand names (Eldepryl, Carbex, Atapryl) and is used to reduce symptoms in early-stage Parkinson's disease. Selegiline delays the time point when the L-DOPA (levodopa) treatment becomes necessary from about 11 months to about 18 months after diagnosis, which is beneficial despite not being definitive evidence of neuroprotection. The rationale for adding selegiline to levodopa is to decrease the required dose of levodopa and thus reduce the motor complications of levodopa therapy. Selegiline is also delivered via a transdermal patch (brand name, Emsam) and in this form, Selegiline is used as a treatment for the major depressive disorder. Selegiline (brand name Anipryl) is also used (at extremely high dosages relative to humans) in veterinary medicine to treat the symptoms of Cushing's disease and cognitive dysfunction (Canine Cognitive Dysfunction) in dogs. Side effects of the pill form include, in decreasing order of frequency, nausea, hallucinations, confusion, depression, loss of balance, insomnia, increased involuntary movements, agitation, arrhythmia, slow heart rate, delusions, hypertension, new or increased angina pectoris, and syncope. The main side effects of the patch form for depression included application site reactions, insomnia, diarrhea, and sore throat.