Melatonin (5-methoxy N-acetyltryptamine) is a hormone synthesized and released from the pineal gland at night, which acts on specific high affinity G-protein coupled receptors to regulate various aspects of physiology and behaviour, including circadian and seasonal responses, and some retinal, cardiovascular and immunological functions. Melatonin is also made synthetically and available without a prescription as an over-the-counter (OTC) dietary supplement in the U.S. Melatonin supplementation has many uses, however, it has been widely studied for treatment of jet lag and sleep disorders. Parents may consider using melatonin to help their child who has a trouble falling asleep. A medical professional should always evaluate insomnia or other sleeping disorders in children. Additionally, melatonin has been shown to protect against oxidative stress in various, highly divergent experimental systems. There are many reasons for its remarkable protective potential. In mammals, melatonin binds to a number of receptor subtypes including high-affinity (MT1 and MT2) and low-affinity (MT3, nuclear orphan receptors) binding sites, which are distributed throughout the central nervous system and periphery.

Aminophenazone is a phenyl-pyrazolone derivative with potent analgesic and antipyretic properties. Aminophenazone has been used as salt or complexes, including topically as the salicylate. It was recommended for the treatment of a fever, neuralgia, myositis, acute rheumatism, arthritis, chorea. In 1999 the FDA suspended aminophenazone. The drug caused agranulocytosis. Some of the cases of agranulocytosis were fatal. Another reason for suspending this drug from the market was its ability to react with nitrite-containing food, thus forming carcinogenic nitrosamines. A breath test with 13C-labeled aminopyrine has been used as a non-invasive measure of cytochrome P-450 metabolic activity in liver function tests.

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.

Phenacetin was used as an analgesic and fever-reducing drug in both human and veterinary medicine for many years. Since a major portion of a dose of phenacetin is rapidly metabolised to paracetamol, it seems possible that phenacetin owes some of its therapeutic activity to its main metabolite, paracetamol, whereas its most troublesome side effect (methaemoglobinaemia) is due to another metabolite, p-phenetidine. Phenacetin was shown to inhibit cyclooxygenase (COX)-3, a cyclooxygenase-1 variant while p-phenetidine potently inhibits both COX-1 and COX-2. There is sufficient evidence in humans for the carcinogenicity of analgesic mixtures containing phenacetin. Analgesic mixtures containing phenacetin cause cancer of the renal pelvis, and of the ureter. Phenacetin was withdrawn from many analgesic mixtures long before the legal ban in several countries.

Antipyrine is an analgesic and antipyretic that has been given by mouth and as ear drops. It is often used in testing the effects of other drugs or diseases on drug-metabolizing enzymes in the liver. It inhibits cyclooxygenases and shows little anti-inflammatory activity. Like many old and approved substances after almost 100 years of use, antipyrine has been associated with some serious side effects, namely agranulocytosis and shock reactions.

Quinine ascorbate is a salt of antimalarial drug quinine and ascorbic acid (vitamin C). Ascorbate reduces the potency of quinolone-containing anti-malarial drugs. Quinine ascorbate was marketed as a component of over-the-counter smoking deterrent products but was not recognized as safe by the FDA regulation in 1993.

Ligustrazine (tetramethylpyrazine) is a bioactive ingredient extracted from the widely-used Chinese herb, Chuanxiong. It inhibits of platelet aggregation, enhances of vessel dilation, increases cerebral blood flow and possesses neuroprotective properties. The injection solution of ligustrazine has been used especially in China to treat ischemic stroke, coronary heart disease, diabetic nephropathy, and knee osteoarthritis. Ligustrazine was also evaluated in clinical as a remedy for pressure sores, as a salvage agent for patients with non-Hodgkin's lymphoma, as a treatment for bronchial asthma and vertebrobasilar insufficiency.

Flotufolastat F 18 (POSLUMA®) is an 18F-labelled radiohybrid (rh) prostate-specific membrane antigen (PSMA)-targeted imaging agent being developed by Blue Earth Diagnostics, a subsidiary of Bracco Imaging, for prostate cancer imaging. In May 2023, flotufolastat F 18 received its first approval in the USA as a radioactive diagnostic agent for positron emission tomography (PET) of PSMA positive lesions in men with prostate cancer with suspected metastasis who are candidates for initial definitive therapy or with suspected recurrence based on elevated serum prostate-specific antigen (PSA) level. Flotufolastat F 18 binds to PSMA (IC50 = 4.4 nM) expressed on cells, including prostate cancer cells, and is internalized. Prostate cancer cells usually overexpress PSMA. Fluorine-18 is a beta emitting radionuclide that can be detected using positron emission tomography.

Berberine, an alkaloid isolated from Rhizoma Coptidis, is known to have a wide array of therapeutic effects including antimicrobial, antineoplastic, and hepatoprotective effects. It is found in several plants including European barberry, goldenseal, goldthread, Oregon grape, phellodendron, and tree tumeric. Berberine seems to slightly reduce blood sugar levels in people with diabetes. Berberine might lower blood pressure. Berberine is possibly safe for most adults for short-term use when taken by mouth or applied to the skin.

Sesamin is the most prominent lignan compound found in sesame seeds, one of the two highest sources of lignans in the human diet (the other being flax). Sesamin is catered to be a nutritional supplement that confers antioxidant and antiinflammatory effects (if touting its health properties) or possibly being an estrogen receptor modulator and fat burner (if targeting atheltes or persons wishing to lose weight). Sesamin has a few mechanisms, and when looking at it holistically it can be summed up as a fatty acid metabolism modifier. It appears to inhibit an enzyme known as delta-5-desaturase (Δ5-desaturase) which is a rate-limiting enzyme in fatty acid metabolism; inhibiting this enzyme results in lower levels of both eicosapentaenoic acid (EPA, one of the two fish oil fatty acids) as well as arachidonic acid, and this mechanism appears to be relevant following oral ingestion. The other main mechanism is inhibiting a process known as Tocopherol-ω-hydroxylation, which is the rate limiting step in the metabolism of Vitamin E; by inhibiting this enzyme, sesamin causes a relative increase of vitamin E in the body but particularly those of the gamma subset (γ-tocopherol and γ-tocotrienol) and this mechanism has also been confirmed to be active following oral ingestion. Sesamin is a potent and specific inhibitor of delta 5 desaturase in polyunsaturated fatty acid biosynthesis. Sesamin inhibits a particular CYP3A enzymes that is involved in vitamin E metabolism, where the enzyme initially ω-hydroxylates vitamin E (required step) and then the rest of vitamin E is subject to fat oxidation. By inhibiting this step, sesamin causes an increase in circulating and organ concentrations of vitamin E. Sesamin is thought to have PPARα activating potential in the liver, but it is uncertain how much practical relevance this has in humans due to this being a mechanism that differs between species.