Side Effects of Salicylates

Salicylates are a commonly used drug for a wide range of conditions, including cardiovascular heart disease, fevers, headaches and muscle aches as well as certain skin conditions. Prolonged use or high doses can lead to undesirable effects, however, as can their use in conjunction with certain medical conditions.

Chemistry

Salicylates are a group of drugs derived from a base structure, called salicylic acid. Salicylic acid itself is corrosive, and is reserved for external use. Alterations to its structure in one of two main locations make the drug safer for ingestion, as well as alter its overall risk for toxicity.

Types

The type of salicylate depends on the alteration to its structure. The main types are acetylated (aspirin) and nonacetylated. Nonacetylated salicylates, such as magnesium choline salicylate and sodium salicylate, are generally less effective than aspirin but may be preferred in certain situations.

Effects

Salicylates affect almost every organ system. From altering the clotting capacity of blood to altering the acid-base balance through the lungs and kidneys, salicylates have a wide reach. They can increase oxygen consumption and carbon dioxide production in the muscles; this shift causes an increased breathing rate (to discharge the extra carbon dioxide produced), which then causes the kidneys to excrete more bicarbonate. Their effect on thromboxane synthesis inhibits the aggregation of platelets. The base compound for the salicylate class, salicylic acid, causes peeling and scaling. Thus, it is used for exfoliative purposes, primarily in certain skin conditions, such as psoriasis, acne and warts.

Function

The salicylates have a wide range of uses. Their antipyretic (antifever) activity and effectiveness in muscle and joint pain are but two of their indications. Low-dose aspirin for cardiovascular disease is a well-known use, as it helps prevent clotting and thus decreases the risk of cardiovascular events (for example, stroke). A study in the New England Journal of Medicine has shown it to be cost effective in this capacity. Further, salicylates are useful in managing inflammatory joint conditions such as rheumatoid arthritis. Finally, salicylic acid is used in dermatology for certain skin conditions.

Warnings

Salicylate poisoning is a very real complication of salicylate therapy, especially in children. The symptoms of salicylate overdose, or intoxication, include coma, convulsions and cardiovascular collapse, including shock. Salicylism refers to mild salicylate intoxication; its symptoms include a ringing in the ears or difficulty hearing, headache, vertigo (dizziness), confusion, drowsiness, nausea, vomiting, thirst, sweating and hyperventilation (rapid breathing). In both cases, the salicylate therapy should be discontinued and medical assistance sought IMMEDIATELY. Should overdosing occur chronically, respiratory failure and death may ensue.

Gastric ulcers are also a risk factor in prolonged salicylate therapy. Such ulcers may lead to gastric bleeding, which may then cause anemia. The risk of gastric ulcers is lower with nonacetylated salicylates, such as magnesium choline salicylate and sodium salicylate.

You should specifically avoid aspirin if you have vitamin K deficiency, liver disease or other conditions in which clotting is impaired. In both cases, aspirin increases the risk of bleeding. Vitamin K is an important cofactor in the production of clotting factors; the liver (along with the kidneys) is responsible for producing thrombopoietin, which matures the cells responsible for producing platelets. Consult your doctor before beginning an aspirin regimen.

References

• Ganong's Review of Medical Physiology, 23e; "Chapter 3: Immunity, Infection & Inflammation"; K. E. Barrett, S. M. Barman, S. Boitano, H. Brooks; 2009
• Goodman & Gilman's The Pharmacological Basis of Therapeutics, 11e; "Chapter 26: Analgesic-Antipyretic and Antiinflammatory Agents; Pharmacotherapy of Gout" A. Burke, E. Smyth, G. Fitzgerald; 2005
• New England Journal of Medicine; Cost Effectiveness of Aspirin, Clopidogrel, or Both for Secondary Prevention of Coronary Heart Disease; J.M. Gaspoz, P.G. Coxson, P.A. Goldman, L.W. Williams, K.M. Kutz, M.G. Myriam, L. Goldman; June 2002