Cantharidin is a toxic compound, isolated from the Spanish fly or blistering beetle (Lytta (Cantharis) vesicatoria) and other insects. It is a potent and specific inhibitor of protein phosphatases 1 (PP1) and 2A (PP2A). Cantharidin is a medication used to remove warts and a viral skin infection called molluscum contagiosum. It is made from the secretions that come from the green blister beetle in combination with salicylic acid. It works by creating a blister just below the wart, which pushes the wart up and away from the underlying tissue, cutting of the blood supply to the wart. As the blister and the wart dry out, they both slough off, leaving fresh, unmarred skin behind. It is also used as an experimental anti-tumor agent. Several studies also show potential novel applications of cantharidin in acquired perforating dermatosis, acute herpes zoster, and leishmaniasis. In 1962, cantharidin lost Food and Drug Administration (FDA) approval owing to the failure of its manufacturers to submit data attesting to cantharidin's efficacy. However, in 1999, the FDA included cantharidin on its “Bulk Substances List” of drugs which although not available as commercial products, were approved for compounding on a customized basis for individual patients.

The mitomycins are a family of aziridine-containing natural products isolated from Streptomyces caespitosus or Streptomyces lavendulae. One of these compounds, mitomycin C, finds use as a chemotherapeutic agent by virtue of its antitumour activity. Mitomycin C has also been used topically rather than intravenously in several areas. The first is cancers, particularly bladder cancers and intraperitoneal tumours. It is now well known that a single instillation of this agent within 6 hours of bladder tumor resection can prevent recurrence. The second is in eye surgery where mitomycin C 0.02% is applied topically to prevent scarring during glaucoma filtering surgery and to prevent haze after PRK or LASIK; mitomycin C has also been shown to reduce fibrosis in strabismus surgery. The third is in esophageal and tracheal stenosis where application of mitomycin C onto the mucosa immediately following dilatation will decrease re-stenosis by decreasing the production of fibroblasts and scar tissue. Mitomycin C is a potent DNA crosslinker. A single crosslink per genome has shown to be effective in killing bacteria. This is accomplished by reductive activation of mitomycin to form a mitosene, which reacts successively via N-alkylation of two DNA bases. Both alkylations are sequence specific for a guanine nucleoside in the sequence 5'-CpG-3'. Potential bis-alkylating heterocylic quinones were synthetised in order to explore their antitumoral activities by bioreductive alkylation. Mitomycin is also used as a chemotherapeutic agent in glaucoma surgery.

Dactinomycin (actinomycin D) was isolated from Streptomyces by Selman Waksman in 1940s. The antibiotic shows anti-cancer activity; it was approved by FDA for the treatment of different cancer conditions among which are Ewing's sarcoma, Wilm's tumor, gestational trophoblastic disease, etc. Dactinomycin exerts its action by binding to DNA (preferably to GC motif) and thus inhibiting transcription.

Ampicillin is a penicillin beta-lactam antibiotic. The following gram-negative and gram-positive bacteria have been shown in in vitro studies to be susceptible to ampicillin: Hemolytic and nonhemolytic streptococci, Streptococcus pneumoniae, Nonpenicillinase-producing staphylococci, Clostridium spp., B. anthracis, Listeria monocytogenes, most strains of enterococci, H. influenzae, N. gonorrhoeae, N. meningitidis, Proteus mirabilis, many strains of Salmonella, Shigella, and E. coli. Ampicillin is indicated in the treatment of bacterial meningitis, septicemia, endocarditis, urinary tract, gastrointestinal, respiratory tract infections caused by susceptible strains of the designated organisms.

Tegafur (INN, BAN, USAN) is a chemotherapeutic fluorouracil prodrug used in the treatment of cancers. It is a component of the combination drugs tegafur/uracil and tegafur/gimeracil/oteracil. UFT is an anticancer medication composed of a fixed molar ration (1:4) of tegafur and uracil. This drug is commonly used in the treatment of head and neck cancer, gastric cancer, colorectal cancer, hepatic cancer, gallbladder cancer, bile-duct cancer, pancreatic cancer, lung cancer, breast cancer, bladder cancer, prostatic cancer, or uterine cervical cancer. In the body, tegafur is converted into 5-fluorouracil (5-FU), the active antineoplastic metabolite. The mechanism of cytotoxicity of 5-FU is thought to be derived from the fact that 5-fluoro-deoxyuridine-monophosphate (FdUMP), the active metabolite of 5-FU, competes with deoxyuridine-monophosphate (dUMP), thereby inhibiting thymidylate synthase and subsequently DNA synthesis. Another active metabolite of 5-FU, 5-fluorouridine-triphosphate (FUTP) is integrated into cellular RNA, inhibiting RNA function. Uracil, when combined with tegafur, enhances the antitumor activity of 5-FU due to higher 5-FU concentrations in the tumor tissue versus normal surrounding tissue compared with tegafur alone. Uracil inhibits degradation of the released 5-FU. The combination of these two drugs enhances the antitumor activity of Tegafur.

Spironolactone is a synthetic 17-lactone steroid which is a renal competitive aldosterone antagonist in a class of pharmaceuticals called potassium-sparing diuretics. On its own, spironolactone is only a weak diuretic, but it can be combined with other diuretics. Due to its anti-androgen effect, it can also be used to treat hirsutism, and is a common component in hormone therapy for male-to-female transgendered people. Spironolactone inhibits the effect of aldosterone by competing for intracellular aldosterone receptor in the distal tubule cells. This increases the secretion of water and sodium, while decreasing the excretion of potassium. Spironolactone has a fairly slow onset of action, taking several days to develop and similarly the effect diminishes slowly. Spironolactone is a specific pharmacologic antagonist of aldosterone, acting primarily through competitive binding of receptors at the aldosterone-dependent sodium-potassium exchange site in the distal convoluted renal tubule. Spironolactone causes increased amounts of sodium and water to be excreted, while potassium is retained. Spironolactone acts both as a diuretic and as an antihypertensive drug by this mechanism. It may be given alone or with other diuretic agents which act more proximally in the renal tubule. Aldosterone interacts with a cytoplasmic mineralocorticoid receptor to enhance the expression of the Na+, K+-ATPase and the Na+ channel involved in a Na+ K+ transport in the distal tubule . Spironolactone bind to this mineralcorticoid receptor, blocking the actions of aldosterone on gene expression. Aldosterone is a hormone; its primary function is to retain sodium and excrete potassium in the kidneys. Spironolactone is used primarily to treat low-renin hypertension, hypokalemia, and Conn's syndrome.

N,N’N’-triethylenethiophosphoramide (ThioTEPA) is a cancer chemotherapeutic member of the alkylating agent group, now in use for over 50 years. It is a stable derivative of N,N’,N’’- triethylenephosphoramide (TEPA). The radiomimetic action of thiotepa is believed to occur through the release of ethylenimine radicals which, like irradiation, disrupt the bonds of DNA. One of the principal bond disruptions is initiated by alkylation of guanine at the N-7 position, which severs the linkage between the purine base and the sugar and liberates alkylated guanines. Thiotepa has been used in the palliation of a wide variety of neoplastic diseases. The more consistent results have been seen in: adenocarcinoma of the breast, adenocarcinoma of the ovary, superficial papillary carcinoma of the urinary bladder and for controlling intracavitary effusions secondary to diffuse or localized neoplastic diseases of various serosal cavities.

Busulfan is a bifunctional alkylating agent, having a selective immunosuppressive effect on bone marrow. It has been used in the palliative treatment of chronic myeloid leukemia (myeloid leukemia, chronic). Most common adverse reactions (incidence greater than 60%) were: myelosuppression, nausea, stomatitis, vomiting, anorexia, diarrhea, insomnia, fever, hypomagnesemia, abdominal pain, anxiety, headache, hyperglycemia and hypokalemia. Itraconazole and acetaminophen can decrease busulfan clearance. Phenytoin increases hepatic clearance of busulfan.

Methotrexate is an antineoplastic anti-metabolite. Anti-metabolites masquerade as purine or pyrimidine - which become the building blocks of DNA. They prevent these substances becoming incorporated in to DNA during the "S" phase (of the cell cycle), stopping normal development and division. Methotrexate inhibits folic acid reductase which is responsible for the conversion of folic acid to tetrahydrofolic acid. At two stages in the biosynthesis of purines and at one stage in the synthesis of pyrimidines, one-carbon transfer reactions occur which require specific coenzymes synthesized in the cell from tetrahydrofolic acid. Tetrahydrofolic acid itself is synthesized in the cell from folic acid with the help of an enzyme, folic acid reductase. Methotrexate looks a lot like folic acid to the enzyme, so it binds to it quite strongly and inhibits the enzyme. Thus, DNA synthesis cannot proceed because the coenzymes needed for one-carbon transfer reactions are not produced from tetrahydrofolic acid because there is no tetrahydrofolic acid. Methotrexate selectively affects the most rapidly dividing cells (neoplastic and psoriatic cells). Methotrexate is indicated in the treatment of gestational choriocarcinoma, chorioadenoma destruens and hydatidiform mole. In acute lymphocytic leukemia, methotrexate is indicated in the prophylaxis of meningeal leukemia and is used in maintenance therapy in combination with other chemotherapeutic agents. Methotrexate is also indicated in the treatment of meningeal leukemia. Methotrexate is used alone or in combination with other anticancer agents in the treatment of breast cancer, epidermoid cancers of the head and neck, advanced mycosis fungoides (cutaneous T cell lymphoma), and lung cancer, particularly squamous cell and small cell types. Methotrexate is also used in combination with other chemotherapeutic agents in the treatment of advanced stage non-Hodgkin’s lymphomas. Methotrexate is indicated in the symptomatic control of severe, recalcitrant, disabling psoriasis. Methotrexate is indicated in the management of selected adults with severe, active rheumatoid arthritis (ACR criteria), or children with active polyarticular-course juvenile rheumatoid arthritis.