Active constituents are usually blamed for untoward reactions however diluents as lactose, drug colorants as the tartrazine or FD and C yellow no. 5 can cause side effects too. These are facts about the common pharmaceutical additives or excipients and their undesirable side effects. Read on.
Penicillin and other antibiotics as tetracycline, cephalosporin and sulphonamide account for most emergency related drug allergies. Ace inhibitors, opiates and NSAIDS as ibuprofen and indomethacin have also been known to be associated with drug sensitivity. While, skin rash, dizziness and stomach upsets are some minor complaints, a life threatening side effect like anaphylaxis can also be possible. With these untoward reactions, we normally suspect the inert substance or the active constituent of the drug. However, excipients or pharmaceutical additives should also be considered too.
Pharmaceutical additives background - types and examples
Pharmaceutical additives or excipients are inactive ingredients that furnish or make up a medicine. Common excipients classified to their functions are the following:
Diluents or fillers are bulking substances. These make up the major portion of a tablet or capsule. Lactose is used often because it is inexpensive, stable and does not react with other medicinal substances. More to this, lactose has rapid solubility in water which is an advantage for the quick release of a drug substance. Other diluents used are starch (from wheat, corn, rice and potato) sucrose, mannitol, avicel and celutab.
Binders or granulating agents are adhesive substances in tablets. These glue together powders to form granules. Binders are added to hold the tablet together and give it strength. Common binders are tragacanth, acacia, sucrose and starch gelatin. For water-sensitive drugs, ethyl cellulose, methyl cellulose in chloroform and polyvinyl pyrolidone (PVP) in alcohol are used.
These are added to tablets to cause them to break apart in aqueous solution. Thus the main function of disintegrants is to oppose the action of binders. Examples of disintegrants are starch, cellulose derivatives (methocel and sodium carboxyl methyl cellulose), avicel and alginates.
Lubricants are additives incorporated in tablets simply to prevent ingredients form clumping together and to avoid the sticking of tablet materials in tablet punches or capsule filling machine. Common lubricants used are talc, silica and fats as magnesium stearate and vegetable stearin.
Colors improve the appearance of a formulation. Manufactures also use these as an identification of their product. Usual dyes used are D and C blue number 9, D & C red no. 6, tartrazine or FD and C yellow number 5, canthaxantin caramel etc.
Sweeteners are essential in liquid oral dosage forms as syrups and suspensions to mask an unpleasant taste in a drug. Flavors are also added for swallowing convenience without water in some tablet types like coated (sugar) and chewable forms. Sucrose is a common flavoring in liquid dosage forms. Others that are used are aspartine, sacharrin, liquid glucose etc.
These are substances that increase the solubility and the availability of active ingredients in a medication. These are usually added in parenteral (dosage forms for injections), topical agents (creams, ointments) and enteral (oral, rectal and sublingual forms of medications). Examples of solubilizers are prophylene glycol, plasdone C and K povidones, cyclodextrins, plasdone K polymers etc.
Preservative are added in drugs to prolong their shelf life. This additive is normally used in liquid formulation and parenteral preparations. Commonly used preservatives are butylated hydroxianizole, butylated hydroxytoluene, benzalkonium chloride, benzyl alcohol etc.
List of diluents causing undesirable side effects:
Most dyes (colorant) – GIT intolerance, contact dermatitis
Tartrazine (colorant) – asthma
Carmine (colorant) – asthma
Prophylene glycol (solubilizer) – lactic acidosis, thromboplebetis, atopic dermatitis, CNS depression, seizure, cardiovascular reactions
Paraben (preservative) – contact dermatitis
Alcohol (solubilizer) – CNS depression, GIT disturbance
Aspartine (sweetener) – headaches, seizure, hypersensitivity reactions
Benzyl alcohol (preservative) – ‘gasping syndrome’, intraverticular hemorrhage, metabolic acidosis, cerebral palsy, hypersensitivity
Benzalkonium chloride (preservative) – bronchoconstriction, pruritus, facial flushing
Saccharin (sweetener) – irritability, hypertonia, strabismus, insomnia
Thiomersal (preservative) – neurotoxicity, behavioral disorder, hypersensitivity reactions
Sulphites (preservative) – bronchospasm
Lactose (diluent) – GIT distress
It is a pharmaceutical ethic and code to have all the drug additives or excipients to be identified and to be guaranteed safe. Excipients are only to be used if necessary and if possible, in the least amount. On the contrary, the formulation of additives is still a trade secret. While some manufactures reveal their list of excipients, most do not cite them in their drug information sheet.
Drug consumers, particularly those who are sentenced to buy their antihypertensive or oral hypoglycemic drugs for life usually compare generic and branded medications in order to save money. While some have been fortunate to find a brand or generic, chemically the same with their expensive brand of maintenance drug, others suffer the consequences of some cheaper drug alternatives. Based on the generic name, branded and other generic equivalents may be the same. However, we must remember that different drug companies do not use the same drug excipients and these additives can be unfavorable for some people.
There is no problem in trying cheaper equivalent types of a drug but if an individual is prone to drug intolerance or hypersensitivity, care is an essence and more importantly, it is always best to consult a doctor.
© Phoenix Montoya @ May 4, 2011
Compiled Notes in Manufacturing Pharmacy by Emma G. Pena MS Pharmacy and Imelda G. Pena Industrial Pharmacy 2010
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