Isometheptene (usually as isometheptene mucate) is a sympathomimetic amine sometimes used in the treatment of migraines and tension headaches due to its vasoconstricting properties. Isometheptene's vasoconstricting properties arise through activation of the sympathetic nervous system via epinephrine and norepinephrine. These compounds elicit smooth muscle activation leading to vasoconstriction by interacting with cell surface adrenergic receptors.

Sulfisoxazole is a sulfonamide antibacterial antibiotic. The sulfonamides are synthetic bacteriostatic antibiotics with a wide spectrum against most gram-positive and many gram-negative organisms. However, many strains of an individual species may be resistant. Sulfisoxazole acetyl in combination with erythromycin ethylsuccinate is used for treatment of ACUTE OTITIS MEDIA in children that is caused by susceptible strains of Haemophilus influenzae. Sulfisoxazole acetyl is a prodrug of sulfisoxazole. Acetyl group is added to make the drug poorly water soluble, and is hydrolyzed in vivo to the active drug. Sulfisoxazole and its acetylated metabolites are excreted primarily by the kidneys through glomerular filtration. Sulfisoxazole is a competitive inhibitor of the enzyme dihydropteroate synthetase. It inhibits bacterial synthesis of dihydrofolic acid by preventing the condensation of the pteridine with para-aminobenzoic acid (PABA), a substrate of the enzyme dihydropteroate synthetase. The inhibited reaction is necessary in these organisms for the synthesis of folic acid

Tolazoline, also known as priscoline, was used in treatment of persistent pulmonary hypertension of the newborn. But that prescription was discontinued. Priscoline given intravenously produces vasodilatation, primarily due to a direct effect on vascular smooth muscle, and cardiac stimulation; the blood pressure response depends on the relative contributions of the two effects. Priscoline usually reduces pulmonary arterial pressure and vascular resistance. The mechanisms of its therapeutic effects are not clear, but is known, that tolazoline is a non-selective competitive α-adrenergic receptor antagonist and it possesses histamine agonist activity.

Tripelennamine (sold as Pyribenzamine by Novartis) is a drug that is used as an antipruritic and first-generation antihistamine. Histamine acting on H1-receptors produces vasodilatation, hypotension, flushing, headache, tachycardia, and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Tripelennamine can be used in the treatment of asthma, hay fever, rhinitis, and urticaria, but is now less common as newer antihistamines have replaced it.

Antazoline is an antagonist of histamine H1 receptors. It selectively bind to but does not activate histamine H1 receptors, thereby blocking the actions of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. Antazoline in combination with naphazoline (VASOCON-A®) is indicated to relieve the symptoms of allergic conjunctivitis.

Sulfamethazine is a sulfonamide used to treat a variety of bacterial diseases in animals. It inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA) for binding to dihydropteroate synthetase (dihydrofolate synthetase).

Tetraethylammonium is an experimental drug with no approved indication or marketed formulation. Tetraethylammonium blocks of apamin-sensitive and insensitive Ca2(+)-activated K+ channels. It is a weak agonist of the nicotinic receptor. Tetraethylammonium produces transient reductions in blood pressure. Tetraethylammonium hydroxide is used as a soluble source of hydroxide ions and in the synthesis of ionic organic compounds.

Tetraethylammonium is an experimental drug with no approved indication or marketed formulation. Tetraethylammonium blocks of apamin-sensitive and insensitive Ca2(+)-activated K+ channels. It is a weak agonist of the nicotinic receptor. Tetraethylammonium produces transient reductions in blood pressure. Tetraethylammonium hydroxide is used as a soluble source of hydroxide ions and in the synthesis of ionic organic compounds.

Tetraethylammonium is an experimental drug with no approved indication or marketed formulation. Tetraethylammonium blocks of apamin-sensitive and insensitive Ca2(+)-activated K+ channels. It is a weak agonist of the nicotinic receptor. Tetraethylammonium produces transient reductions in blood pressure. Tetraethylammonium hydroxide is used as a soluble source of hydroxide ions and in the synthesis of ionic organic compounds.

Tetraethylammonium is an experimental drug with no approved indication or marketed formulation. Tetraethylammonium blocks of apamin-sensitive and insensitive Ca2(+)-activated K+ channels. It is a weak agonist of the nicotinic receptor. Tetraethylammonium produces transient reductions in blood pressure. Tetraethylammonium hydroxide is used as a soluble source of hydroxide ions and in the synthesis of ionic organic compounds.