Thiabendazole is a fungicide and parasiticide. Tiabendazole works by inhibition of the mitochondrial, helminth-specific enzyme, fumarate reductase, with possible interaction with endogenous quinone. Tiabendazole serves to block angiogenesis in both frog embryos and human cells. It has also been shown to serve as a vascular disrupting agent to reduce newly established blood vessels. Tiabendazole has been shown to effectively do this in certain cancer cells.

Tetrahydrofolic acid, or tetrahydrofolate, is a folic acid derivative. Tetrahydrofolic acid is a cofactor in many reactions, especially in the metabolism of amino acids and nucleic acids. Tetrahydrofolic acid acts as a donor of a group with one carbon atom. It gets this carbon atom by sequestering formaldehyde produced in other processes.

Terlipressin is an analogue of vasopressin used as a vasoactive drug in the management of low blood pressure. It has been found to be effective when norepinephrine does not help. Indications for use include norepinephrine-resistant septic shock and hepatorenal syndrome. In addition, it is used to treat bleeding esophageal varices. Terlipressin is currently not available in the United States, or Canada, but it is available in New Zealand, Australia, much of Europe, India & UAE.

Terbutaline is a β2 adrenergic receptor agonist, used as a "reliever" inhaler in the management of asthma symptoms and as a tocolytic (anti-contraction medication) to delay preterm labor for up to 48 hours. This time can then be used to administer steroid injections to the mother which help fetal lung maturity and reduce complications of prematurity. It should not be used to prevent preterm labor or delay labor more than 48–72 hours.

Tamsulosin is an α1a adrenergic receptor antagonist used in the symptomatic treatment of benign prostatic hyperplasia (BPH). Tamsulosin is used in the treatment of difficult urination, a common symptom of enlarged prostate. Tamsulosin, and other medications in the class called alpha blockers, work by relaxing bladder neck muscles and muscle fibers in the prostate itself and make it easier to urinate.

Tacrine is a centrally acting anticholinesterase and indirect cholinergic agonist. It is approved for the treatment of Alzheimer's disease.

Sulfisoxazole is a sulfonamide antibacterial with an oxazole substituent. It has antibiotic activity against a wide range of Gram-negative and Gram-positive organisms.

Sulfapyridine is a sulfonamide antibacterial. At one time it was commonly referred to as M&B. Sulfapyridine is no longer prescribed for treatment of infections in humans. However, it may be used to treat linear IgA disease. It is a good antibacterial drug, but its water solubility is very pH dependent. Thus there is a risk of crystallization within the bladder or urethra, which could lead to pain or blockage. As with other sulfonamides, there is a significant risk of agranulocytosis, and this, rather than the development of resistance by bacteria, is the main reason for its decline in use.

Sulfanilamide is a sulfonamide antibacterial. Chemically, it is an organic compound consisting of an aniline derivatized with a sulfonamide group. sulfanilamide remains in use for treatment of vaginal yeast infections.

Sulfamoxole is a sulfonamide antibacterial.

Sulfametopyrazine is a long-acting sulfonamide antibacterial used for the treatment of chronic bronchitis, urinary tract infections and malaria.

Sulfamethoxazole is an antibiotic. It was used for bacterial infections such as urinary tract infections, bronchitis, and prostatitis and is effective against both gram negative and positive bacteria such as Listeria monocytogenes and E. coli. Common side effects include nausea, vomiting, loss of appetite, and a rash. It is a sulfonamide and bacteriostatic.

Sulfadimethoxine is a sulfonamide antibiotic. Albon is produced by Pfizer Animal Health and is available as an oral suspension, tablet or bolus. It is used to treat many infections including treatment of respiratory, urinary tract, enteric, and soft tissue infections. It is most frequently used in veterinary medicine. Sulfadimethoxine inhibits bacterial synthesis of folic acid (pteroylglutamic acid) from para-aminobenzoic acid. It is also commonly used for the treatment of coccidiosis in many species.

Sulfadiazine eliminates bacteria that cause infections by stopping the production of folate inside the bacterial cell, and is commonly used to treat urinary tract infections, and burns. In combination, sulfadiazine and pyrimethamine, can be used to treat toxoplasmosis.

Sulfacetamide has anti-inflammatory properties when used to treat blepharitis or conjunctivitis (in eye-drop solution). It is believed to work by limiting the presence of folic acid which bacteria need to survive. It has been suggested that sulfacetamide may also serve as a treatment for mild forms of hidradenitis suppurativa. Sulfacetamide has antibacterial activity and is used to control acne.

Suxamethonium Chloride, also known as Succinylcholine, is a medication used to induce muscle relaxation and short-term paralysis, usually to help with tracheal intubation. It is sometimes used in combination with pain medications and sedatives for euthanasia and immobilization of horses. )

Streptomycin is an antibiotic (antimycobacterial) drug, the first of a class of drugs called aminoglycosides to be discovered, and it was the first effective treatment for tuberculosis. It is derived from the actinobacterium Streptomyces griseus. Streptomycin is a bactericidal antibiotic. Adverse effects of this medicine are ototoxicity, nephrotoxicity, fetal auditory toxicity, and neuromuscular paralysis.

Spirapril is an ACE inhibitor antihypertensive drug used to treat hypertension. It belongs to dicarboxy group of ACE inhibitors.

Spectinomycin is an antibiotic useful for the treatment of gonorrhea infections. It is given by injection into a muscle. Common side effects include pain at the area of injection, rash, nausea, fever, and trouble sleeping.

Sparfloxacin trade names Spacin in Bangladesh, Zagam and Zagam Respipac, is a fluoroquinolone antibiotic used in the treatment of bacterial infections.

Spaglumic Acid is a peptide neurotransmitter and the third-most-prevalent neurotransmitter in the mammalian nervous system. NAAG consists of N-acetylaspartic acid (NAA) and glutamic acid coupled via a peptide bond.

Selegiline hydrochloride is a selective, irreversible inhibitor of Type B monoamine oxidase. It is used in newly diagnosed patients with Parkinson's disease. It may slow progression of the clinical disease and delay the requirement for levodopa therapy. It also may be given with levodopa upon onset of disability.

Rolitetracycline is a tetracycline antibiotic that may be given intravenously or intramuscularly in serious bacterial infections when oral administration is not practicable.

Remoxipride Hydrochloride (anhydrous) is a selective and potent D2DR (dopamine D2 receptor) antagonist with very modest efficacy against D3RD and D4RD receptors.

Ranitidine hydrochloride is a histamine H2-receptor antagonist used in the treatment of gastrointestinal lesions due to excessive gastric acid secretion.

Quinethazone is a thiazide diuretic used to treat hypertension. Common side effects include dizziness, dry mouth, nausea, and low potassium levels.

Quinestrol is a compound used in estrogen replacement therapy.

Quinapril Hydrochloride is an angiotensin-converting enzyme inhibitor. Quinapril is a prodrug that is converted to its active metabolite, quinaprilat. Quinapril’s target catalyses the formation of angiotensin II from its precursor, angiotensin I. Angiotensin II is a potent vasoconstrictor and thus preventing its formation causes vasodilation and an increased capillary blood volume.

Pyridostigmine Bromide is a cholinesterase inhibitor with a slightly longer duration of action than neostigmine. It is used in the treatment of myasthenia gravis and to reverse the actions of muscle relaxants.Pyridostigmine bromide binds reversibly to acetylcholinesterase active sites in the peripheral nervous system, thereby preventing the breakdown of acetylcholine. This leads to an accumulation of acetylcholine at cholinergic synapses and facilitates transmission of impulses across the neuromuscular junction.

Protriptyline Hydrochloride is a tricyclic secondary amine with antidepressant property. Protriptyline hydrochloride blocks the re-uptake of norepinephrine and serotonin by nerve terminals, thereby increasing available norepinephrine and serotonin. Protriptyline does not block dopamine transport but may have an indirect dopamine-facilitating effect through interactions of increased peri-synaptic abundance of norepinephrine, particularly in the cerebral cortex, where adrenergic terminals exceed dopaminergic terminals. This results in elevation of mood and behavioral activity. In addition, this agent exhibits anticholinergic activity.