Antitubercular drugs are used to treat tuberculosis (TB), which is caused by Mycobacterium tuberculosis. Not always curative, these drugs can halt the progression of a mycobacterial infection. These drugs also are effective against less common mycobacterial infections caused by M. kansasii, M. avium-intracellulare, M. fortuitum, and related organisms. Unlike most antibiotics, antitubercular drugs may need to be administered over many months. This creates problems, such as patient noncompliance, the development of bacterial resistance, and drug toxicity.
Traditionally, isoniazid, rifampin, and ethambutol were the mainstays of multidrug TB therapy and successfully prevented the emergence of drug resistance. Because of the current incidence of drug-resistant TB strains, a four-drug regimen is now recommended for initial treatment:
Isoniazid
Rifampin
Pyrazinamide
Streptomycin or ethambutol
Several other drugs are used as antitubercular drugs in combination with first-line drugs. Because these drugs have a greater incidence of toxicity, they’re used primarily for the patient who’s resistant or allergic to less toxic drugs.
Fluoroquinolones, such as ciprofloxacin and ofloxacin, are effective against Mycobacterium tuberculosis. Of these two drugs, ofloxacin is more potent and may be an initial choice in retreatment. These drugs are administered orally and are generally well tolerated. GI adverse reactions are most commonly reported. However, resistance to fluoroquinolones develops rapidly when these drugs are used alone or in insufficient doses.
Streptomycin was the first drug recognized as effective in treating tuberculosis. Streptomycin is administered I.M. only. It appears to enhance the activity of oral antitubercular drugs and is of greatest value in the early weeks to months of therapy. However, I.M. administration limits its usefulness in long-term therapy. Rapidly absorbed from the I.M. injection site, streptomycin is excreted primarily by the kidneys as unchanged drug. Most patients tolerate streptomycin well, but those receiving large doses may exhibit eighth cranial nerve toxicity (ototoxicity).
The antitubercular regimen should be modified if local testing shows resistance to one or more of these drugs. If local outbreaks of TB resistant to isoniazid and rifampin are occurring in facilities (for example, health care facilities), then five- or six-drug regimens are recommended as initial therapy.
Most antitubercular drugs are administered orally. When administered orally, these drugs are well absorbed from the GI tract and widely distributed throughout the body. They’re metabolized primarily in the liver and excreted by the kidneys.
多数抗结核病药为口服药。口服时，这些药物GI吸收良好，并分布全身。药物主要经肝代谢，经肾排出。
Vocabulary for Today
antitubercular – a. 抗结核病的
mycobacterium – n. 分枝杆菌
M. kansasii – n. 堪萨斯分枝杆菌
M. avium-intracellulare – n. 鸟-胞内分枝杆菌
M. fortuitum – n. 偶发分枝杆菌
isoniazid – n. 异烟肼
rifampin – n. 利福平
ethambutol – n. 乙胺丁醇
mainstay – n. 骨干，主流
pyrazinamide – n. 吡嗪酰胺
streptomycin – n. 链霉素
fluoroquinolone – n. 氟喹诺酮
ciprofloxacin – n. 环丙沙星
ofloxacin – n. 氧氟沙星
Test 1.A client with a productive cough, chills, and night sweats is suspected of having active TB. The physician should take which of the following actions?
A. Admit him to the hospital in respiratory isolation
B. Prescribe isoniazid and tell him to go home and rest
C. Give a tuberculin test and tell him to come back in 48 hours and have it read.
D. Give a prescription for isoniazid, 300 mg daily for 2 weeks, and send him home.
2.Which of the following antituberculous drugs can cause damage to the eighth cranial nerve?
A. Streptomycin
B. Isoniazid
C. Para-aminosalicylic acid
D. Ethambutol hydrochloride
本期ISPN Review答案 1.A.Admit him to the hospital in respiratory isolation.
The client is showing s/s of active TB and because of a productive cough is highly contagious. He should be admitted to the hospital, placed in respiratory isolation, and three sputum cultures should be obtained to confirm the diagnosis. He would most likely be given isoniazid and two or three other antitubercular antibiotics until the diagnosis is confirmed, then isolation and treatment would continue if the cultures were positive for TB. After 7 to 10 days, three more consecutive sputum cultures will be obtained. If they’re negative, he would be considered non-contagious and may be sent home, although he’ll continue to take the antitubercular drugs for 9 to 12 months.
2.A.Streptomycin.
Streptomycin is an aminoglycoside, and eight cranial nerve damage (ototoxicity) is a common side effect from aminoglycosides.
当前位置：
