MT Training > pharmacology

Drug Toxicity

Drug toxicity is 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 are based on the dosage of the drug given. Physicians are trained to be aware of the potential toxic effects of all drugs that they prescribe.

Iatrogenic (produced by treatment) disorders can occur, however, as a result of mistakes in drug use or of individual sensitivity to a given agent.

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

Contraindications are factors in a patient’s condition that make the use of a drug dangerous and ill advised. For example, in the presence of renal failure, it is unwise to administer a drug that is normally eliminated by the kidneys. Excess drug will accumulate in the body and cause side effects.

Classes of Drugs

The following are major classes of drugs with explanations of their use in the body. The names of specific drugs are included in tables for your reference (trade or brand names are capitalized; generic names begin with a small letter).

Analgesics

An analgesic (alges/o means sensitivity to pain) is a drug that relieves pain. Mild analgesics are used for mild to moderate pain, such as caused by myalgias, headache, and toothache. More potent analgesics are narcotics or opioids, because they contain or are derived from opium. These are used only to relieve severe pain because they may produce dependence (habit formation) and tolerance. Morphine is an example of a narcotic analgesic.

Some non-narcotic analgesics reduce fever, pain, and inflammation and are used in rheumatic (joint) disorders.

These agents are not steroid hormones (such as cortisone) and are known as nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs act on tissues to inhibit prostaglandins (hormone-like substances that sensitize peripheral pain receptors).

Table 4-2. Analgesics

Anesthetics

An anesthetic is an agent that reduces or eliminates sensation. This can affect the whole body (general anesthetic) or a particular region (local anesthetic). General anesthetics are used for surgical procedures and depress the activity of the central nervous system producing loss of consciousness. Local anesthetics inhibit the conduction of impulses in sensory nerves in the region in which they are injected or applied.

Table 4-2 gives examples of specific anesthetics.

Antibiotics

An antibiotic is a chemical substance produced by a microorganism that inhibits or stops the growth of bacteria, fungi, or parasites. The use of antibiotics has largely controlled many diseases such as pneumonia, rheumatic fever, and mastoiditis. Caution about the use of antibiotics is warranted because they are powerful agents. With indiscriminate use, pathogenic organisms can develop resistance to the antibiotic and thus destroy the antibiotic’s disease-fighting capability.

Table 4-3. Antibiotics with Specific examples

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