DRUG TOXICITY

Drug toxicity refers to the poisonous and potentially dangerous effects of some drugs. Idiosyncrasy is an example of an unpredictable type of drug toxicity.

Other types of drug toxicity are more predictable and based on the dosage of the drug given. If the dosage of certain drugs is increased, un­favorable effects may be produced. Physicians are trained to be aware of the potential toxic effects of all drugs they prescribe and must be cautious with their use. Disorders directly resulting from diagnostic or thera­peutic efforts of a physician are known as iatrogenic, and are usually related to drug toxicity.

Side effects are toxic effects which routinely result from the use of a drug. They often occur with the usual therapeutic dosage of a drug and are usually tolerable. For example, nausea, vomiting, and alopecia are common side effects of the chemotherapeutic drugs used to treat cancer.

Contraindications are factors in a patient's condition which make the use of a drug dangerous. For example, in the presence of renal failure, it is unwise to administer a drug which is normally elimi­nated by the kidneys.

Among the most dangerous toxic complications of drug usage are blood dyscrasias (blood diseases) such as aplastic anemia and leukopenia, cataract formation (eye disorder), cholestatic jaundice (biliary obstruc­tion leading to yellow discoloration of skin), neuropathy, collagen disor­ders (connective tissue damage such as arthritis), and photosensitivity (abnornmal sensitivity to light).