Lactose is the most important carbohydrate in the milk of most species. Its biosynthesis takes place in the mammary gland. The molecular structures of α- and β -lactose differ in the orientation of a hydrogen- and a hydroxyl group on carbon atom no.1 in the glucose moiety. Both forms change into one another continuously. At room temperature, the equilibrium results in a ratio of about 40% α-lactose and 60% β-lactose. The fact that two forms of lactose exist which differ in molecular structure has profound effects on various properties of lactose such as crystallization behavior, crystal morphology, solid-state properties, and solubility. The intestine does not actively absorb lactose unless it is split into its two-monosaccharide components, i.e. glucose and galactose. This hydrolysis of lactose is affected by the enzyme lactase, which is produced by the epithelium cells in the brush-border of the small intestine. Thus, the capacity of mammals to digest lactose is dependent on the lactase activity in the intestine. The maximum activity of the enzyme occurs shortly after birth and declines during the weaning period, after which it remains at a relatively constant level. Genetically determined factors governing residual lactase activity also exist. Individuals having low lactase activity are called lactose malabsorbers. Lactose intolerance is a condition in which people have symptoms due to the decreased ability to digest lactose. The principal symptom of lactose intolerance is an adverse reaction to products containing lactose (primarily milk), including abdominal bloating and cramps, flatulence, diarrhea, nausea, borborygmi, and vomiting (particularly in adolescents). These appear one-half to two hours after consumption.

Benzyl benzoate is an organic compound with the formula C6H5CH2O2CC6H5. It is the ester of benzyl alcohol and benzoic acid. It forms either a viscous liquid or solid flakes and has a weak, sweet-balsamic odor. It occurs in a number of blossoms (e. g. tuberose, hyacinth) and is a component of Balsam of Peru and Tolu balsam. It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system. Benzyl benzoate is one of the older preparations used to treat scabies. Scabies is a skin infection caused by the mite sarcoptes scabiei. It is characterised by severe itching (particularly at night), red spots, and may lead to a secondary infection. Benzyl benzoate is lethal to this mite and so is useful in the treatment of scabies. It is also used to treat lice infestation of the head and body. Benzyl benzoate is not the treatment of choice for scabies due to its irritant properties. Benzyl benzoate exerts toxic effects on the nervous system of the parasite, resulting in its death. It is also toxic to mite ova, though its exact mechanism of action is unknown. In vitro, benzyl benzoate has been found to kill the Sarcoptes mite within 5 minutes.

Homatropine (used in a form of bromide or methylbromide salts) is an analogue of atropine, which acts as an antagonist of muscarinic receptors. Homatropine was approved for the treatment of cough in combination with hydrocodone bitartrate.

Phenylmercuric nitrate is classified as an antimicrobial preservative. It is bactericidal against many Gram-positive and Gram-negative species. It is used as antimicrobial preservative mainly in ophthalmic preparations. Patients who used eye drops containing the preservative, phenylmercuric nitrate for from 3 to 15 years, developed a brownish pigmentation of the anterior capsule of the pupillary area. Special studies, including electron microprobe analysis and neutron activation analysis established the presence of mercury in a lens with mercurialentis. Phenylmercuric nitrate is also an effective spermicide, although its use in vaginal contraceptives is no longer recommended.

Sucrose is a disaccharide composed of glucose and fructose, and found in many plants and plant parts. Sucrose is often extracted and refined from either sugarcane or beet sugar for human consumption. Upon ingestion, sucrose is hydrolyzed in the small intestine by by sucrase to glucose and fructose. Sucrose is used as inactive ingredients in numerous drugs. In medicine, sucrose is used for pain relief in infants.

Chlorobutanol, or trichloro-2-methyl-2-propanol, is an analgesic and sedative hypnotic in man, and an experimental general anesthetic. It has antibacterial and antifungal properties. It is also used chemical preservative for parenteral drugs. It was found, that chlorobutanol inhibited mammalian Nav 1.2 channels at concentrations less than those used to preserve parenteral solutions. Its mechanism of inhibiting Na channels differs from that of local anesthetics in that it does not show use dependent or state dependent inhibition.

Noscapine (also known as Narcotine, Nectodon, Nospen, Anarcotine and (archaic) Opiane) is a benzylisoquinoline alkaloid from plants of the poppy family, without painkilling properties. This agent is primarily used for its antitussive (cough-suppressing) effects. Noscapine is often used as an antitussive medication. A 2012 Dutch guideline, however, does not recommend its use for coughing. Noscapine can increase the effects of centrally sedating substances such as alcohol and hypnotics. Noscapine should not be taken in conjunction with warfarin as the anticoagulant effects of warfarin may be increased. Noscapine, and its synthetic derivatives called noscapinoids, are known to interact with microtubules and inhibit cancer cell proliferation. Mechanisms for its antitussive action are unknown, although animal studies have suggested central nervous system as a site of action. Furthermore, noscapine causes apoptosis in many cell types and has potent antitumor activity against solid murine lymphoid tumors (even when the drug was administered orally) and against human breast and bladder tumors implanted in nude mice. Because noscapine is water-soluble and absorbed after oral administration, its chemotherapeutic potential in human cancer merits thorough evaluation. Antifibrotic effect of noscapine based on novel mechanism, which it shows through EP2 prostaglandin E2 receptor-mediated activation of protein kinase A.

Diethyl ether (ether) had been widely used for anesthesia until the 1960s despite its explosive properties and toxicity to both humans and animals. Diethyl ether still serves a role today as an effective inhalation agent. Newer inhalation agents have replaced ether completely and open drop delivery systems have been exchanged for complicated vaporizers and monitoring systems. Anesthesia in the developing world, however, still closely resembles primitive anesthetics.

Diethyltoluamide (DEET) is an insect repellent used to keep insects away. This product is effective against mosquitoes, biting flies (gnats, sandflies, deer flies, stable flies, black flies), ticks, harvest mites, and fleas. DEET is absorbed through the skin. DEET has few adverse effects when applied as directed. The most common problem is local skin irritation, including erythema and pruritis, at the site of application.