Dibucaine (USAN) is an amide local anesthetic. Dibucaine reversibly binds to and inactivates sodium channels in the neuronal cell membrane. Inhibition of sodium channels prevents the depolarization of nerve cell membranes and inhibits subsequent propagation of impulses along the course of the nerve, thereby limiting the excitation of nerve endings. This results in loss of sensation. Among the most potent and toxic of the long-acting local anesthetics, current use of dibucaine is generally restricted to spinal and topical anesthesia. It is sold under the brand names Cincain, Nupercainal, Nupercaine and Sovcaine. (Source: https://en.wikipedia.org/wiki/Cinchocaine).

Diatrizoic acid (or its anionic form, diatrizoate), also known as amidotrizoic acid, or 3,5-diacetamido-2,4,6-triiodobenzoic acid, is a radiocontrast agent containing iodine. Trade names include Hypaque, Gastrografin and Urografin, the latter being a combination of the sodium and meglumine salts. Diatrizoate is considered a high-osmolality contrast agent.

Dextrothyroxine (trade name Choloxin) saw research as an cholesterol-lowering drug but was pulled due to cardiac side-effects. It also increases hepatic lipase which in turn improves utilization of triglycerides, improving apolipoprotein E cholesterol particles. (Source: https://en.wikipedia.org/wiki/Dextrothyroxine).

Dexmedetomidine, sold under the trade names Precedex and Dexdor, among others, is an anxiolytic, sedative, and analgesic medication. Similar to clonidine, it is an agonist of α2-adrenergic receptors in certain parts of the brain. Dexmedetomidine is notable for its ability to provide sedation without risk of respiratory depression (unlike other commonly used sedatives such as propofol, fentanyl, and midazolam) and can provide cooperative or semi-arousable sedation. Dexmedetomidine hydrochloride is also used in veterinary medicine for dogs and cats. The drug was developed by Orion Pharma. (Source: https://en.wikipedia.org/wiki/Dexmedetomidine).

Desvenlafaxine (brand name: Pristiq, Desfax), also known as O-desmethylvenlafaxine, is an antidepressant of the serotonin-norepinephrine reuptake inhibitor (SNRI) class developed and marketed by Wyeth (now part of Pfizer). Desvenlafaxine is a synthetic form of the major active metabolite of venlafaxine (sold under the brand names Effexor and Efexor). It is being targeted as the first non-hormonal based treatment for menopause. Desvenlafaxine is a synthetic phenethylamine bicyclic derivative with antidepressant activity. Desvenlafaxine is a selective reuptake inhibitor of serotonin and norepinephrine due to its high binding affinities to the pre-synaptic serotonin and norepinephrine transporters. By blocking both transporters, this agent prolongs neurotransmitter activities of both serotonin and norepinephrine, thereby alleviating depressive state. (Source: https://en.wikipedia.org/wiki/Desvenlafaxine).

Demeclocycline (INN, BAN) (brand names Declomycin, Declostatin, Ledermycin, Bioterciclin, Deganol, Deteclo), also known as demeclocycline hydrochloride (USAN) (brand names Detravis, Meciclin, Mexocine, Clortetrin), is a semisynthetic tetracycline antibiotic which was derived from a strain of Streptomyces aureofaciens. Demeclocycline binds to bacterial 30S ribosomal subunit and prevents binding of aminoacyl-tRNA to the mRNA-ribosome complex, thereby inhibiting protein synthesis. Demeclocycline also inhibits the effect of vasopressin on the renal tubules, thereby causing diuresis. (Source: https://en.wikipedia.org/wiki/Demeclocycline).

Deferoxamine is a bacterial siderophore produced by the Actinobacteria Streptomyces pilosus. It has medical applications as a chelating agent used to remove excess iron from the body. The mesylate salt of DFO-B is commercially available. It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system. Deferoxamine acts by binding free iron in the bloodstream and enhancing its elimination in the urine.

Decamethonium (Syncurine) is a depolarizing muscle relaxant or neuromuscular blocking agent, and is used in anesthesia to induce paralysis. Decamethonium, which has a short action time, is similar to acetylcholine and acts as a partial agonist of the nicotinic acetylcholine receptor. In the motor endplate, it causes depolarization, preventing further effects to the normal release of acetylcholine from the presynaptic terminal, and therefore preventing the neural stimulus from affecting the muscle.

Debrisoquine is a derivative of guanidine. It is an antihypertensive drug similar to guanethidine. Debrisoquine is frequently used for phenotyping the CYP2D6 enzyme, a drug metabolizing enzyme.

Dantrolene sodium is a postsynaptic muscle relaxant that lessens excitation-contraction coupling in muscle cells. It achieves this by inhibiting Ca2+ ions release from sarcoplasmic reticulum stores by antagonizing ryanodine receptors. It is the primary drug used for the treatment and prevention of malignant hyperthermia, a rare, life-threatening disorder triggered by general anesthesia. It is also used in the management of neuroleptic malignant syndrome, muscle spasticity (e.g. after strokes, in paraplegia, cerebral palsy, or patients with multiple sclerosis), and 2,4-dinitrophenol poisoning.

Dalfampridine is a potassium channel blocker used to help multiple sclerosis patients walk. This is the first drug that was specifically approved to help with mobility in these patients. It has been approved by the FDA for use as a treatment for multiple sclerosis.

Cyclopentolate is a parasympatholytic anticholinergic used solely to obtain mydriasis or cycloplegia. It is commonly used during pediatric eye examinations to dilate the eye (mydriatic), prevent accommodation of the eye to different distances (cycloplegic), and block specific receptors called muscarinic receptors (muscarinic antagonist). Cyclopentolate is also administered as an atropine substitute to reverse muscarinic and central nervous system effects of indirect cholinomimetic (anti-AChase) administration.

Cyclandelate is a direct-acting smooth muscle relaxant vasodilator used in the treatment of claudication, arteriosclerosis and Raynaud's disease. It is also used to treat nighttime leg cramps, and has been investigated for its effect against migraine. It is orally administered.

Cromoglicic acid , cromolyn (USAN), cromoglycate (former BAN), or cromoglicate, is traditionally described as a mast cell stabilizer, and is commonly marketed as the sodium salt sodium cromoglicate or cromolyn sodium. This drug prevents the release of inflammatory chemicals such as histamine from mast cells. Because of their convenience (and perceived safety), leukotriene receptor antagonists have largely replaced it as the non-corticosteroid treatment of choice in the treatment of asthma. Cromoglicic acid requires administration four times daily, and does not provide additive benefit in combination with inhaled corticosteroids.

Cloxacillin is an antibiotic useful for the treatment of a number of bacterial infections. It is semisynthetic and in the same class as penicillin. Cloxacillin is used against staphylococci that produce beta-lactamase, due to its large R chain, which does not allow the beta-lactamases to bind. This drug has a weaker antibacterial activity than benzylpenicillin, and is devoid of serious toxicity except for allergic reactions. Cloxacillin was discovered and developed by Beecham. It is sold under a number of trade names, including Cloxapen, Cloxacap, Tegopen and Orbenin. It is on the World Health Organization's List of Essential Medicines, the most important medication needed in a basic health system.

Clomifene or clomiphene is a selective estrogen receptor modulator (SERM) that has become the most widely prescribed drug for ovulation induction to reverse anovulation or oligoovulation. Clomiphene is a triphenylethylene nonsteroidal ovulatory stimulant evaluated for antineoplastic activity against breast cancer. Clomiphene has both estrogenic and anti-estrogenic activities that compete with estrogen for binding at estrogen receptor sites in target tissues. This agent causes the release of the pituitary gonadotropins follicle stimulating hormone (FSH) and luteinizing hormone (LH), leading to ovulation. It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system.

Clofibrate (Atromid-S) is an aryloxyisobutyric acid derivate with antihyperlipidemic activity. It is marketed as a fibrate. It is a lipid-lowering agent used for controlling the high cholesterol and triacylglyceride level in the blood. It increases lipoprotein lipase activity to promote the conversion of VLDL to LDL, and hence reduce the level of VLDL. It can increase the level of HDL as well.

Clidinium bromide is an anticholinergic drug, specifically a muscarinic antagonist. It may help symptoms of cramping and abdominal/stomach pain by decreasing stomach acid, and slowing the intestines. It is commonly prescribed in combination with chlordiazepoxide using the brand name Librax.

Clenbuterol Hydrochloride is a sympathomimetic β2-adrenoceptor agonist that has been used as a bronchodilator in the treatment of pulmonary diseases such as asthma. At higher doses, clenbuterol acts as an anabolic steroid, favoring skeletal muscle protein synthesis at the expense of fat deposition.

Clemastine fumarate is a histamine H1 antagonist used as the hydrogen fumarate in hay fever, rhinitis, allergic skin conditions, and pruritus. Clemastine fumarate blocks the H1 histamine receptor and prevents the symptoms that are caused by histamine activity on capillaries, bronchial and gastrointestinal smooth muscles, including vasodilation, increased capillary permeability, bronchoconstriction, and spasmodic contraction of gastrointestinal smooth muscles. It may cause cause drowsiness. This drug also prevents histamine-induced pain and itching of mucous membranes.

Clavulanate potassium is an acid which is a suicide inhibitor of bacterial beta-lactamase enzymes from Streptomyces clavuligerus. Administered alone, it has only weak antibacterial activity against most organisms, but when combined with penicillin-group antibiotics it prevents antibiotic inactivation by microbial lactamase. It is commonly combined with amoxicillin or ticarcillin.

Ciprofloxacin hydrochloride is a broad-spectrum antimicrobial carboxyfluoroquinoline, an fluoroquinolone antibiotic that is widely used as an antimicrobial and immunomodulatory agent. It is capable of inducing respiratory, urinary tract, gastrointestinal, and abdominal infections. It functions by inhibiting DNA gyrase (a type II topoisomerase) and topoisomerase IV, the enzymes responsible for negative supercoiling of chromosomes and DNA strand separation, thus blocking initiation of bacterial replication. Most recently ciprofloxacin has been used in the management of postexposure inhalational anthrax and radiation combined injury resulting from nuclear disasters.

Cinoxacin was an older synthetic antimicrobial related to the quinolone class of antibiotics with activity similar to oxolinic acid and nalidixic acid. It was commonly used thirty years ago to treat urinary tract infections in adults. There are reports that cinoxacin had also been used to treat initial and recurrent urinary tract infections and bacterial prostatitis in dogs however this veterinary use was never approved by the FDA. In complicated UTI, the older gyrase-inhibitors such as cinoxacin are no longer indicated.

Cinolazepam is a benzodiazepine derivative drug. It possesses anxiolytic, anticonvulsant, sedative and skeletal muscle relaxant properties. Due to its strong sedative properties, it is primarily used as an hypnotic.

Cinitapride is a gastroprokinetic agent and medication prescribed to treat conditions caused by an overactive digestive tract. It slows the actions of the muscles to reduce the symptoms of conditions such as acid reflux, ulcer dyspepsia, and delayed gastric emptying. It acts as an agonist of the 5-HT1 and 5-HT4 receptors and as an antagonist of the 5-HT2 receptors.

Cinalukast is a potent, selective CysLT1 (LTD4) leukotriene receptor antagonist. It is used in the treatment of asthma, cinalukast selectively antagonizes leukotriene D4 (LTD4) at the cysteinyl leukotriene receptor, CysLT1, in the human airway. Cinalukast inhibits the actions of LTD4 at the CysLT1 receptor, preventing airway edema, smooth muscle contraction, and enhanced secretion of thick, viscous mucus.

Chlorpropamide is a drug in the sulfonylurea class used to treat type 2 diabetes mellitus. It is a long-acting 1st generation sulfonylurea. Chlorpropamide acts to increase the secretion of insulin, so it is only effective in patients who have some pancreatic beta cell function.

Chloroxine is a synthetic antibacterial agent. It inhibits the growth of Gram-positive and some Gram-negative bacteria and also induces SOS-DNA repair. Chlorxine shows bacteriostatic, fungistatic and antiprotozoal effects in vivo.

Chloropyramine is a first generation antihistamine drug approved for the treatment of allergic conjunctivitis, allergic rhinitis, bronchial asthma, and other atopic (allergic) conditions. Chloropyramine is known as a competitive reversible H1-receptor antagonist, meaning that it exerts its pharmacological action by competing with histamine for the H1 subtype histamine receptor. By blocking the effects of histamine, the drug inhibits the vasodilation, increased vascular permeability, and tissue edema associated with histamine release in the tissue.

Chloroprocaine Hydrochloride is a synthetic, local anesthetic agent. At the injection site, chloroprocaine hydrochloride acts by inhibiting sodium influx through binding to specific membrane sodium ion channels in the neuronal cell membranes, restricting sodium permeability, and blocking nerve impulse conduction. This leads to a loss of sensation. Chloroprocaine hydrochloride is short-acting due to rapid hydrolysis by pseudocholinesterase into para-aminobenzoic acid in plasma.