Chemicals in pharmaceutical drugs include the active drug and excipients, other substances that account for most of the weight or volume of a medicinal product and function to guarantee dosage, stability and bioavailability of the drug, according to "The Safety of Pharmaceutical Excipients" by Giorgio Pifferi. Chemicals also differentiate, enhance appearance and retain quality of drugs, according to research by E. Vranic published in "Bosnian Journal of Basic Medical Science" in 2004.
Active Pharmaceutical Ingredients
There are four classes of active pharmaceutical ingredients, according to Humphrey Moynihan, author of the book "Physicochemical Basis of Pharmaceuticals." Psychopharmacological agents, such as clonazepam and oxycodone, are compounds that act on the central nervous system; these drugs include antidepressants, antipsychotics, anticonvulsants, anxiolytics, psychomimetics, analgesics, hypnotics, sedatives and anti-Parkinsonian agents.
Pharmacodynamic agents, such as warfarin and fexofenadine, interact with normal processes of the body, such as blood circulation or digestion; these drugs include anti-hypertensives, antithrombotics, vasodilators, antianginals, antiarrhymics, vasodilators and anti-allergy and anti-ulcer drugs. Chemotherapeutic agents, such as methotrexate, amoxicillin and ribavirin, treat infections and cancer and include antibiotics, antiparasites, antivirals and antifungals. Agents that act on endocrine and metabolic functions, such as insulin, exenetide and infliximab, include hormones and drugs that treat diabetes, inflammation, arthritis and atherosclerosis.
Excipients
Excipients are chemical components of drugs other than active ingredients and are classified by the function they perform in dosage formulations, according to Humphrey Moynihan. Diluents, also called fillers, increase bulk or volume in a tablet or capsule; these include calcium phosphates, carbonates and carbohydrates such as glucose, sucrose, sorbitol, lactose cellulose, mannitol or starch. Surfactants contain both hydrophobic and hydrophilic regions and are used in suspensions, emulsions and solutions to keep the product uniform. Lubricants, such as paraffin, magnesium stearate, polyethylene glycol and sodium dodecyl sulfate, are used to reduce friction between powders and metal surfaces during manufacturing of tablets. Disintegrants, such as cellulose and crospovidone, help break up tablets. Viscosity enhancers, such as xanthan gum, are added to liquid formulations to ease pouring and sedimentation of suspensions. Binders or adhesives, such as polyvinylpyyrolidone, hold powders together in tablets.
Preservatives, Dyes and Flavorings
Prescription drugs can contain chemical preservatives, dyes and flavorings, according to research conducted by A.P. Balbani and published in the "Brazilian Journal of Otorhinolaryngology" in 2006. Preservatives, such as methylparaben and propylparaben, extend quality and shelf life of drugs. Dyes such as tartrazine, also called FD&C yellow no. 5, and sunset yellow dye, also called FD&C yellow no. 6, are used to identify and differentiate drugs. Flavoring agents, such as fruit, are used to enhance taste and compliance of the drug.
References
- Elsevier: The Safety of Pharmaceutical Excipients
- "Bosnian Journal of Basic Medical Science"; Basic Principles of Drug--Excipients Interactions; E. Vranic; May 2004
- "Physicochemical Basis of Pharmaceuticals"; H. Moynihan; 2009
- "International Journal of Pharmaceutics"; New Findings on Melatonin Absorption Excipients; H.T. Tran; Aug 2009
- "Current Drug Metabolism"; Recent Advances in Pharmacokinetics of Excipients; N.V. Cuong; Oct 2009
