ISPN Review Contraindications and Cautions
禁忌与注意事项
Aminoglycosides are contraindicated in the following conditions: known allergy to any of the aminoglycosides; renal or hepatic disease that could be exacerbated by toxic aminoglycoside effects and that could interfere with drug metabolism and excretion, leading to higher toxicity; preexisting hearing loss, which could be intensified by toxic drug effects on the auditory nerve; active infection with herpes or mycobacterial infections that could be worsened by the effects of an aminoglycoside on normal defense mechanisms; myasthenia gravis or parkinsonism, which often are exacerbated by the effects of a particular aminoglycoside on the nervous system; and lactation, because aminoglycosides are excreted in breast milk and potentially could cause serious effects in the infant. Caution is necessary when these agents are administered during pregnancy because aminoglycosides are used to treat only severe infections, and the benefits of the drug must be carefully weighed against potential adverse effects on the fetus. It is necessary to test urine function frequently when these drugs are used because they depend on the kidney for excretion and are toxic to the kidney.
The potential for nephrotoxicity and ototoxicity with amikacin is very high, so the drug is used only as long as absolutely necessary. Do not use kanamycin for longer than 7 to 10 days, because of its potential toxic effects, which include renal damage, bone marrow depression, and GI complications. Streptomycin, once a commonly used drug, is reserved for use in special situations because is very toxic to the eighth cranial nerve and kidney. It can be used in severe infections if the organism has been shown to be sensitive to streptomycin and no less-toxic drugs can be used.
The many serious adverse effects associated with aminoglycosides limit their usefulness. The drugs come with a black box warning alerting health care professionals to the serious risk of ototoxicity and nephrotoxicity. Central nervous system (CNS) effects include ototoxicity, possibly leading to irreversible deafness; vestibular paralysis resulting from drug effects on the auditory nerve; confusion; depression; disorientation; and numbness, tingling, and weakness related to drug effects on other nerves.
Renal toxicity, which may progress to renal failure, is caused by direct drug toxicity in the glomerulus, meaning that the drug molecules cause damage (e.g., obstruction) directly to the kidney. Bone marrow depression may result from direct drug effects on the rapidly dividing cells in the bone marrow, leading, for example, to immune suppression and resultant superinfections.
GI effects include nausea, vomiting, diarrhea, weight loss, stomatitis, and hepatic toxicity. These effects are a result of direct GI irritation, loss of bacteria of the normal flora with resultant superinfections, and toxic effects in the mucous membranes and liver as the drug is metabolized.
GI 效应包括恶心、呕吐、腹泻、体重减轻、口炎、肝毒性。这些效应的原因是直接的GI炎症、正常菌群细菌丧失伴二重感染；粘膜毒性效应及药物代谢时的肝毒性。
Cardiac effects can include palpitations, hypotension, and hypertension. Hypersensitivity reactions include purpura, rash, urticaria, and exfoliative dermatitis.
心脏效应可能包括心悸、低血压、高血压。超敏反应包括紫癜、皮疹、荨麻疹、剥脱性皮炎。
Vocabulary for Today
aminoglycoside – n. 氨基糖苷类药
exacerbate – v. 加重，加剧
preexisting – a. 预成的
intensify – v. 强化，使激烈
myasthenia gravis – 重症肌无力
parkinsonism – n. 帕金森症
amikacin – n. 阿米卡星
kanamycin – n. 卡那霉素
exfoliative dermatitis – 剥脱性皮炎
Tests 1. Both IV ampicillin/sulbactam (Unasyn) and gentamicin (Garamycin) are ordered for a patient. When administering these medications, the nurse will do what?
A. Ensure that separate IV solutions are used.
B. Use two different peripheral IV sites.
C. Administer the gentamicin first.
D. There are no necessary precautions.
2. The nurse knows that there is an increased risk of ototoxicity in a patient receiving an aminoglycoside if which level is high?
本期ISPN Review答案： 1. A. Ensure that separate IV solutions are used.
When penicillins are present in high concentrations, they interact chemically with aminoglycosides, causing inactivation of the aminoglycoside. Therefore, penicillins and aminoglycosides should not be mixed in the same IV solution. Rather, these drugs should be administered separately. Two different peripheral IV sites are not necessary. Administering the gentamicin first does not ensure separation of the two medications.
2. B. Trough
When trough levels remain elevated, aminoglycosides are unable to diffuse out of inner ear cells, thus exposing the cells to the medication for an extended time. Prolonged exposure (i.e., high trough levels), rather than brief exposure to high levels, underlies cellular injury.
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