Mercaptopurine, marketed under the brand name Purinethol among others, is a medication used for cancer and autoimmune diseases. Mercaptopurine competes with hypoxanthine and guanine for the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRTase) and is itself converted to thioinosinic acid (TIMP). This intracellular nucleotide inhibits several reactions involving inosinic acid (IMP), including the conversion of IMP to xanthylic acid (XMP) and the conversion of IMP to adenylic acid (AMP) via adenylosuccinate (SAMP). In addition, 6-methylthioinosinate (MTIMP) is formed by the methylation of TIMP. Both TIMP and MTIMP have been reported to inhibit glutamine-5-phosphoribosylpyrophosphate amidotransferase, the first enzyme unique to the de novo pathway for purine ribonucleotide synthesis. Experiments indicate that radiolabeled mercaptopurine may be recovered from the DNA in the form of deoxythioguanosine. Some mercaptopurine is converted to nucleotide derivatives of 6-thioguanine (6-TG) by the sequential actions of inosinate (IMP) dehydrogenase and xanthylate (XMP) aminase, converting TIMP to thioguanylic acid (TGMP). PURINETHOL (mercaptopurine) is indicated for maintenance therapy of acute lymphatic (lymphocytic, lymphoblastic) leukemia as part of a combination regimen. The response to this agent depends upon the particular subclassification of acute lymphatic leukemia and the age of the patient (pediatric or adult).

Hydralazine is a direct-acting vasodilator that is used as an antihypertensive agent. Hydralazine works by relaxing blood vessels (arterioles more than venules) and increasing the supply of blood and oxygen to the heart while reducing its workload. It also functions as an antioxidant. It inhibits membrane-bound enzymes that form reactive oxygen species, such as superoxides. Excessive superoxide counteracts NO-induced vasodilation. Hydralazine is used for the treatment of essential hypertension, alone or as an adjunct. Also for the management of severe hypertension when the drug cannot be given orally or when blood pressure must be lowered immediately, congestive heart failure (in combination with cardiac glycosides and diuretics and/or with isosorbide dinitrate), and hypertension secondary to pre-eclampsia/eclampsia.

Pyrimethamine, sold under the trade name Daraprim, is one of the folic acid antagonists that is used as an antimalarial or with a sulfonamide to treat toxoplasmosis. In addition it was approved in Chemoprophylaxis of Malaria. However, resistance to pyrimethamine is prevalent worldwide. It is not suitable as a prophylactic agent for travelers to most areas. Pyrimethamine is well absorbed with peak levels occurring between 2 to 6 hours following administration. It is eliminated slowly and has a plasma half-life of approximately 96 hours. Pyrimethamine is 87% bound to human plasma proteins. Pyrimethamine acts by selectively inhibiting malarial dihydrofolate reductase-thymidylate synthase and the rationale for its therapeutic action is based on the differential requirement between host and parasite for nucleic acid precursors involved in growth. This activity is highly selective against plasmodia and Toxoplasma gondii. Pyrimethamine possesses blood schizonticidal and some tissue schizonticidal activity against malaria parasites of humans. The action of pyrimethamine against Toxoplasma gondii is greatly enhanced when used in conjunction with sulfonamides.

Erythromycin cyclocarbonate (Davercin) is a first generation semi-synthetic erythromycin. It is active against Gram-positive and some Gram-negative microorganisms. Davercin shows comparable or better in vitro potency, low host toxicity and improved pharmacokinetics compared with erythromycin. It is approved for the treatment of acne, atypical pneumonia (caused by Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila), whooping cough (treatment and prevention), urethritis (caused by Ureaplasma urealyticum and Chlamydia trachomatis), gastrointestinal infection caused by Campylobacter spp., short-term infections of the skin and soft tissues (e.g. acne, staphylococcal dermatitis). In streptococcal infections, diphtheria, gonorrhea, early syphilis in patients who are allergic to penicillin, and in the prevention of bacterial endocarditis before the planned dental procedures. Adverse effects are: nausea, vomiting, abdominal pain, diarrhea, skin allergic reactions.

Isoniazid is a bactericidal agent active against organisms of the genus Mycobacterium, specifically M. tuberculosis, M. bovis and M. kansasii. Isoniazid is recommended for all forms of tuberculosis in which organisms are susceptible. Isoniazid is a prodrug and must be activated by bacterial catalase. Isoniazid inhibits InhA, the enoyl reductase from Mycobacterium tuberculosis, by forming a covalent adduct with the NAD cofactor. The most frequent adverse reactions to isoniazid are those affecting the nervous system and the liver.

Primaquine is a oral medication used to treat and prevent malaria and to treat Pneumocystis pneumonia. Specifically it is used for malaria due to Plasmodium vivax and Plasmodium ovale along with other medications and for prevention if other options cannot be used. Primaquine is an alternative treatment for Pneumocystis pneumonia together with clindamycin. Primaquine is lethal to P. vivax and P. ovale in the liver stage, and also to P. vivax in the blood stage through its ability to do oxidative damage to the cell. However, the exact mechanism of action is not fully understood. Primaquine is well-absorbed in the gut and extensively distributed in the body without accumulating in red blood cells. Administration of primaquine with food or grapefruit juice increases its oral bioavailibity. In blood, about 20% of circulating primaquine is protein-bound, with preferential binding to the acute phase protein orosomucoid. With a half-life on the order of 6 hours, it is quickly metabolized by liver enzymes to carboxyprimaquine, which does not have anti-malarial activity. Common side effects of primaquine administration include nausea, vomiting, and stomach cramps. Primaquine phosphate is recommended only for the radical cure of vivax malaria, the prevention of relapse in vivax malaria, or following the termination of chloroquine phosphate suppressive therapy in an area where vivax malaria is endemic. Patients suffering from an attack of vivax malaria or having parasitized red blood cells should receive a course of chloroquine phosphate, which quickly destroys the erythrocytic parasites and terminates the paroxysm. Primaquine phosphate should be administered concurrently in order to eradicate the exoerythrocytic parasites in a dosage of 1 tablet (equivalent to 15 mg base) daily for 14 days.

Methimazole (also known as Tapazole or Thiamazole or MMI) is an antithyroid drug. Methimazole binds to thyroid peroxidase and thereby inhibits the conversion of iodide to iodine. Thyroid peroxidase normally converts iodide to iodine (via hydrogen peroxide as a cofactor) and also catalyzes the incorporation of the resulting iodide molecule onto both the 3 and/or 5 positions of the phenol rings of tyrosines found in thyroglobulin. Thyroglobulin is degraded to produce thyroxine (T4) and tri-iodothyronine (T3), which are the main hormones produced by the thyroid gland. So methimazole effectively inhibits the production of new thyroid hormones. Methimazole is used for the treatment of hyperthyroidism, goiter, Graves disease and psoriasis.

Ascorbic acid (vitamin C) is a water-soluble vitamin. It occurs as a white or slightly yellow crystal or powder with a slight acidic taste. Ascorbic acid is an electron donor, and this property accounts for all its known functions. As an electron donor, ascorbic acid is a potent water-soluble antioxidant in humans. Ascorbic acid acts as an antioxidant under physiologic conditions exhibiting a cross over role as a pro-oxidant in pathological conditions. Oxidized ascorbic acid (dehydroascorbic acid (DHA) directly inhibits IkappaBalpha kinase beta (IKKbeta) and IKKalpha enzymatic activity in vitro, whereas ascorbic acid did not have this effect. These findings define a function for vitamin C in signal transduction other than as an antioxidant and mechanistically illuminate how vitamin C down-modulates NF-kappaB signaling. Vitamin C is recommended for the prevention and treatment of scurvy. Its parenteral administration is desirable for patients with an acute deficiency or for those whose absorption of orally ingested ascorbic acid (vitamin c) is uncertain. Symptoms of mild deficiency may include faulty bone and tooth development, gingivitis, bleeding gums, and loosened teeth. Febrile states, chronic illness, and infection (pneumonia, whooping cough, tuberculosis, diphtheria, sinusitis, rheumatic fever, etc.) increase the need for ascorbic acid (vitamin c). Hemovascular disorders, burns, delayed fracture and wound healing are indications for an increase in the daily intake.

Niacinamide, known as nicotinamide, is an important compound functioning as a component of the coenzyme NAD. Its primary significance is in the prevention and/or cure of blacktongue and pellagra. Pellagra is a nutritional disease that occurs due to insufficient dietary amounts of vitamin B3 or the chemical it is made from (tryptophan). Symptoms of pellagra include skin disease, diarrhea, dementia, and depression. In addition, was experiments, revealed, that niacinamide hydroiodide might have role in ophthalmology and parenteral use of niacinamide hydroiodide can treat arteriosclerotic syndromes.

Ethinyl estradiol is a synthetic derivative of the natural estrogen estradiol. It is one of two estrogens currently used in oral contraceptive pills. The other, mestranol, is converted to ethinyl estradiol before it is biologically active. Ethinyl estradiol and norethindrone are used together as an oral contraceptive agent. Estrogens diffuse into their target cells and interact with a protein receptor. Target cells include the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Estrogens increase the hepatic synthesis of sex hormone binding globulin (SHBG), thyroid-binding globulin (TBG), and other serum proteins and suppress follicle-stimulating hormone (FSH) from the anterior pituitary. This cascade is initiated by initially binding to the estrogen receptors. The combination of an estrogen with a progestin suppresses the hypothalamic-pituitary system, decreasing the secretion of gonadotropin-releasing hormone (GnRH). Used for treatment of moderate to severe vasomotor symptoms associated with the menopause, female hypogonadism, prostatic carcinoma-palliative therapy of advanced disease, breast cancer, as an oral contraceptive, and as emergency contraceptive.