Rifabutin is an antibiotic that inhibits DNA-dependent RNA polymerase activity in susceptible cells. Specifically, it interacts with bacterial RNA polymerase but does not inhibit the mammalian enzyme. It is bactericidal and has a very broad spectrum of activity against most gram-positive and gram-negative organisms (including Pseudomonas aeruginosa) and specifically Mycobacterium tuberculosis. It is FDA approved for the prophylaxis of disseminated Mycobacterium avium complex (MAC) disease in patients with advanced HIV infection. Multiple dosing of rifabutin has been associated with induction of hepatic metabolic enzymes of the CYP3A subfamily. Rifabutin’s predominant metabolite (25-desacetyl rifabutin: LM565), may also contribute to this effect. Similarly, concomitant medications that competitively inhibit the CYP3A activity may increase plasma concentrations of rifabutin. Common adverse reactions include discoloration of skin, rash, diarrhea, disorder of taste, indigestion, loss of appetite, nausea, vomiting, increased liver aminotransferase level (mild), ocular discoloration, uveitis, abnormal color of body fluid.

Zolpidem is usually used for the treatment of insomnia as a hypnotic drug. It was also suggested to be effective in the treatment of dystonia in some studies. Zolpidem can be one of useful alternative pharmacological treatments for blepharospasm. Zolpidem interacts with a GABA-BZ receptor complex and shares some of the pharmacological properties of the benzodiazepines. In contrast to the benzodiazepines, which non-selectively bind to and activate all BZ receptor subtypes, zolpidem in vitro binds the BZ1 receptor preferentially with a high affinity ratio of the α1/α5 subunits. This selective binding of zolpidem on the BZ1 receptor is not absolute, but it may explain the relative absence of myorelaxant and anticonvulsant effects in animal studies as well as the preservation of deep sleep in human studies of zolpidem tartrate at hypnotic doses.

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.

Paroxetine, also known by the trade names Paxil and Seroxat. PAXIL (paroxetine hydrochloride) is an orally administered psychotropic drug. It is the hydrochloride salt of a phenylpiperidine compound identified chemically as (-)-trans-4R-(4'fluorophenyl)-3S-[(3',4'-methylenedioxyphenoxy) methyl] piperidine hydrochloride hemihydrate. It is used to treat major depressive disorder, obsessive-compulsive disorder, social anxiety disorder, panic disorder, posttraumatic stress disorder, generalized anxiety disorder and premenstrual dysphoric disorder. Paroxetine is a potent and highly selective inhibitor of neuronal serotonin reuptake. Paroxetine likely inhibits the reuptake of serotonin at the neuronal membrane, enhances serotonergic neurotransmission by reducing turnover of the neurotransmitter, therefore it prolongs its activity at synaptic receptor sites and potentiates 5-HT in the CNS; paroxetine is more potent than both sertraline and fluoxetine in its ability to inhibit 5-HT reuptake. Compared to the tricyclic antidepressants, SSRIs have dramatically decreased binding to histamine, acetylcholine, and norepinephrine receptors. The mechanism of action for the treatment of vasomotor symptoms is unknown. Paroxetine, a phenylpiperidine derivative, was originally developed in 1975 by Jorgen Buus-Lassen and associates working in a small Danish company Ferrosan. Paroxetine was the second SSRI synthesized by Buus-Lassen In 1975.

Simvastatin is a HMG-CoA Reductase Inhibitor that is FDA approved for the treatment of hypercholesterolemia and for the reduction in the risk of cardiac heart disease mortality and cardiovascular events. It reduces levels of "bad" cholesterol (low-density lipoprotein, or LDL) and triglycerides in the blood, while increasing levels of "good" cholesterol (high-density lipoprotein, or HDL). Common adverse reactions include abdominal pain, constipation, nausea, headache, upper respiratory infection. Cases of myopathy/rhabdomyolysis have been observed with simvastatin co-administered with lipid-modifying doses ( ≥ 1 g/day niacin) of niacin-containing products. The risk of myopathy, including rhabdomyolysis, is increased by concomitant administration of amiodarone, dronedarone, ranolazine, or calcium channel blockers such as verapamil, diltiazem, or amlodipine.

Clarithromycin is an antibacterial drug which is used either in combination with lansoprazole and amoxicillin (Prevpac), in combination with omeprazole and amoxicillin (Omeclamox) or alone (Biaxin) for the treatment of broad range of infections. The drug exerts its action by binding to 23s rRNA (with nucleotides in domains II and V). The binding leads to the protein synthesis inhibition and the cell death.

Etodolac is an anti-inflammatory agent with analgesic and antipyretic properties. It is used to treat osteoarthritis, rheumatoid arthritis and control acute pain. The therapeutic effects of etodolac are achieved via inhibition of the synthesis of prostaglandins involved in fever, pain, swelling and inflammation. Etodolac is administered as a racemate. As with other NSAIDs, the S-form has been shown to be active while the R-form is inactive. Both enantiomers are stable and there is no evidence of R- to S- conversion in vivo. Similar to other NSAIDs, the anti-inflammatory effects of etodolac result from inhibition of the enzyme cycooxygenase (COX). This decreases the synthesis of peripheral prostaglandins involved in mediating inflammation. Etodolac binds to the upper portion of the COX enzyme active site and prevents its substrate, arachidonic acid, from entering the active site. Etodolac was previously thought to be a non-selective COX inhibitor, but it is now known to be 5 – 50 times more selective for COX-2 than COX-1. Antipyresis may occur by central action on the hypothalamus, resulting in peripheral dilation, increased cutaneous blood flow, and subsequent heat loss. Etodolac is used for acute and long-term management of signs and symptoms of osteoarthritis and rheumatoid arthritis, as well as for the management of pain. Lodine, the brand-name formulation of the drug, has been discontinued in the United States, and only the generic form of etodolac is available.

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.

Sertraline (trade names Zoloft and others) is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. Sertraline is primarily prescribed for major depressive disorder in adult outpatients as well as obsessive-compulsive disorder, panic disorder, and social anxiety disorder, in both adults and children. The exact mechanism of action sertraline is not fully known, but the drug appears to selectively inhibit the reuptake of serotonin at the presynaptic membrane. This results in an increased synaptic concentration of serotonin in the CNS, which leads to numerous functional changes associated with enhanced serotonergic neurotransmission. It is suggested that these modifications are responsible for the antidepressant action observed during long-term administration of antidepressants. It has also been hypothesized that obsessive-compulsive disorder is caused by the dysregulation of serotonin, as it is treated by sertraline, and the drug corrects this imbalance. Compared to other SSRIs, sertraline tends to be associated with a higher rate of psychiatric side effects and diarrhea. It tends to be more activating (that is, associated with a higher rate of anxiety, agitation, insomnia, etc.) than other SSRIs, aside from fluoxetine. Over a two-week treatment of healthy volunteers, sertraline slightly improved verbal fluency but did not affect word learning, short-term memory, vigilance, flicker fusion time, choice reaction time, memory span, or psychomotor coordination. In spite of lower subjective rating, that is, feeling that they performed worse, no clinically relevant differences were observed in the objective cognitive performance in a group of people treated for depression with sertraline for 1.5 years as compared to healthy controls

Ticlopidine (trade name Ticlid) is an antiplatelet drug in the thienopyridine family which is an adenosine diphosphate (ADP) receptor inhibitor. Ticlopidine is a prodrug that is metabolized to an as yet undetermined metabolite that acts as a platelet aggregation inhibitor. Inhibition of platelet aggregation causes a prolongation of bleeding time. In its prodrug form, ticlopidine has no significance in vitro activity at the concentrations attained in vivo. The active metabolite of ticlopidine prevents binding of adenosine diphosphate (ADP) to its platelet receptor, impairing the ADP-mediated activation of the glycoprotein GPIIb/IIIa complex. It is proposed that the inhibition involves a defect in the mobilization from the storage sites of the platelet granules to the outer membrane. No direct interference occurs with the GPIIb/IIIa receptor. As the glycoprotein GPIIb/IIIa complex is the major receptor for fibrinogen, its impaired activation prevents fibrinogen binding to platelets and inhibits platelet aggregation. Ticlopidine is FDA approved for the prevention of strokes and, when combined with aspirin, for patients with a new coronary stent to prevent closure. There are also several off-label uses, including acute treatment of myocardial infarction and unstable angina, peripheral vascular disease, prevention of myocardial infarctions, diabetic retinopathy, and sickle cell disease. The most serious side effects associated with ticlopidine are those that affect the blood cells, although these life-threatening complications are relatively rare.