McKenna's Pharmacology, 2e

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C H A P T E R 3  Toxic effects of drugs

mucous membrane lesions and vaginal discharge with or without itching. Interventions Provide supportive measures (frequent mouth care, skin care, access to bathroom facilities, small and frequent meals). Administer antifungal therapy as appropriate. In severe cases, discontinue the drug responsible for the superinfection. Blood dyscrasia Blood dyscrasia is bone marrow suppression caused by drug effects. This occurs when drugs that can cause cell death (e.g. antineoplastics, antibiotics) are used. Bone marrow cells multiply rapidly; they are said to be rapidly turning over. Because they go through cell division and multiply so often, they are highly susceptible to any agent that disrupts cell function. Assessment Symptoms include fever, chills, sore throat, weakness, back pain, dark urine, decreased haematocrit (anaemia), low platelet count (thrombocytopenia), low white blood cell count (leucopenia) and a reduction of all cellular elements of the full blood count (pancytopenia). Interventions Monitor blood counts. Provide supportive measures (rest, protection from exposure to infections, protection from injury, avoidance of activities that might result in injury or bleeding). In severe cases, discontinue the drug or stop administration until the bone marrow recovers to a safe level. ■■ Adverse drug effects can include skin irritation ranging from rashes and hives to potentially fatal Stevens–Johnson syndrome. Adverse effects can be predictable or unpredictable based on the mechanism of action of the drug to its drug profile. ■■ Other adverse drug effects include superinfections, or infections caused by destruction of protective normal flora bacteria; blood dyscrasias caused by bone marrow suppression of the blood-forming cells; and stomatitis or mucous membrane eruptions. Toxicity Introducing chemicals into the body can sometimes affect the body very severely. These effects are not acceptable adverse effects but are potentially serious reactions to a drug. When a drug is known to have toxic effects, the benefit of the drug to the person must be weighed against the possibility of toxic effects causing harm. KEY POINTS KEY POINTS

Central nervous system effects

Ocular damage

Auditory damage

Stomatis

Dermatological reactions

Allergic reactions

Liver damage

Renal damage

Bone marrow depression

Teratogenicity

FIGURE 3.1  Variety of adverse effects and toxicities associated with drug use.

Other symptoms include difficulty swallowing, bad breath, and pain in the mouth and throat. Interventions Provide frequent mouth care with a non-irritating solution. Offer nutrition evaluation and development of a tolerated diet, which usually involves frequent, small meals. If necessary, arrange for a dental consultation. Note that antifungal agents and/or local anaesthetics are sometimes used. Superinfections One of the body’s protective mechanisms is provided by the wide variety of bacteria that live within or on the surface of the body. This bacterial growth is called the normal flora. Normal flora protect the body from invasion by other bacteria, viruses, fungi and so on. Several kinds of drugs (especially antibiotics) destroy the normal flora, leading to the development of superinfec- tions , or infections caused by organisms that are usually controlled by the normal flora. Assessment Symptoms can include fever, diarrhoea, a black or hairy tongue, an inflamed and swollen tongue (glossitis),