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.

Chlorhexidine digluconate solution is a bis-biguanide family cationic broad spectrum antibiotic. Studies indicate that chlorhexidine digluconate solution functions, via destabilization of the outer bacterial membrane, which resulted in the release of periplasmic enzymes in gram negative bacteria. In addition, Chlorhexidine digluconate solution inhibits oxygen utilization which leads to a reduction in bacterial ATP. Furthermore, Chlorhexidine digluconate solution is very effective against bacteria such as Propionibacterium, Selenomonas, and cocci resembling Veillonella.

Cephalexin is a cephalosporin antibiotic used to study the effect of expression, binding, and inhibition of PBP3 and other penicillin-binding proteins on bacterial cell wall mucopeptide synthesis. Cephalexin disrupts the synthesis of the peptidoglycan layer of bacterial cell walls which is responsible for cell wall structural integrity. Peptidoglycan synthesis is facilitated by transpeptidases known as penicillin-binding proteins.

Cefuroxime sodium is a broad-spectrum cephalosporin antibiotic useful in infections of gram-negative and gram-positive organisms, gonorrhea, and haemophilus.

Ceftriaxone sodium is an antibiotic, a third-generation cephalosporin. Like other third-generation cephalosporins, it has broad-spectrum activity against Gram-positive bacteria and expanded Gram-negative coverage compared to second-generation agents. This includes pneumonia, ear infections, skin infections, urinary tract infections, gonorrhea, pelvic inflammatory disease, septisis, bone and joint infections, intra-abdominal infections, and meningitis. It is also used preoperatively to reduce the risk of postoperative infections. It is administered by intravenous or intramuscular injection.

Ceftizoxime is third generation cephalosporin effective against Gram-negative and Gram-positive bacteria. It binds penicillin-binding proteins (PBPs) and inhibits the bacterial cell wall synthesis. Unlike other third-generation cephalosporins, the whole C-3 side chain in ceftizoxime has been removed to prevent deactivation by hydrolytic enzymes. It rather resembles cefotaxime in its properties, but is not subject to metabolism.

Ceftazidime is a broad-spectrum β-lactam antibiotic used as an antimicrobial agent. It is used for treating febrile neutropenia in patients with cancer. It is a third-generation cephalosporin. As a class, cephalosporins have activity against Gram-positive and Gram-negative bacteria. The balance of activity tips toward Gram-positive organisms for earlier generations; later generations of cephalosporins have more Gram-negative coverage. Ceftazidime is one of the few in this class with activity against Pseudomonas.

Cefprozil, under the marketed trade name Cefzil, is a second-generation cephalosporin type antibiotic. It can be used to treat bronchitis, ear infections, skin infections, and other bacterial infections. It comes as a tablet and as a liquid suspension. Cefprozil's effect is dependent on its binding to penicillin-binding proteins (PBPs) located in the bacterial cytoplasmic membrane. Binding results in the inhibition of the transpeptidase enzymes, thereby preventing cross-linking of the pentaglycine bridge with the fourth residue of the pentapeptide and interrupting consequent synthesis of peptidoglycan chains. As a result, cefprozil inhibits bacterial septum and cell wall synthesis formation.