ISPN Review Pharmacokinetics of Nucleoside Reverse Transcriptase Inhibitors
核苷逆转录酶抑制剂的药代动力学
Abacavir is an oral drug that is rapidly absorbed from the GI tract. It is metabolized in the liver and excreted in feces and urine with a half-life of 1 to 2 hours.
阿巴卡韦为口服药，经胃肠道快速吸收，经肝代谢，经粪便和尿排出，半衰期1-2h。
Didanosine is rapidly destroyed in an acid environment and therefore must be taken in a buffered form. It reaches peak levels in 15 to 75 minutes. Didanosine undergoes intracellular metabolism with a half-life of 8 to 24 hours. It is excreted in the urine.
Emtricitabine has the advantage of being a one-capsule a- day therapy. Emtricitabine has a rapid onset and peaks in 1 to 2 hours. It has a half-life of 10 hours, and after being metabolized in the liver is excreted in the urine and feces. Dose needs to be reduced in patients with renal impairment. It has been associated with severe and even fatal hepatomegaly with steatosis, a fatty degeneration of the liver.
Lamivudine is rapidly absorbed from the GI tract and is excreted primarily unchanged in the urine. It peaks within 4 hours and has a half-life of 5 to 7 hours. Because excretion depends on renal function, dose reduction is recommended in the presence of renal impairment. The drug is available as an oral solution, Epivir-HBV, it is also recommended for the treatment of chronic hepatitis B.
Stavudine is rapidly absorbed from the GI tract, reaching peak levels in 1 hour. Most of the drug is excreted unchanged in the urine, making it important to reduce dose and monitor patients carefully in the presence of renal dysfunction. It can be used for adults and children and is only available in an extended-release form, allowing for once-a-day dosing.
Tenofovir is a newer drug used only in combination with other antiretroviral agents. It is rapidly absorbed from the GI tract, reaching peak levels in 45 to 75 minutes. Its metabolism is not known, but it is excreted in the urine.
Zalcitabine is used to treat advanced cases of HIV/AIDS in adults, as a monotherapy in adults who have become intolerant to zidovudine or who have progressive disease while taking zidovudine, and as combination therapy with zidovudine for the treatment of advanced HIV infection. After absorption from the GI tract, zalcitabine is excreted unchanged in the urine with a half-life of 2 hours.
Zidovudine was one of the first drugs found to be effective in the treatment of AIDS. It is rapidly absorbed from the GI tract, with peak levels occurring within 30 to 75 minutes. Zidovudine is metabolized in the liver and excreted in the urine, with a half-life of 1 hour.
abacavir – n. 阿巴卡韦
didanosine – n. 去羟肌苷
emtricitabine – n. 恩曲他滨
steatosis – n. 脂肪变性
lamivudine – n. 拉米夫定
Epivir – n. 益平维
stavudine – n. 司他夫定
tenofovir – n. 替诺福韦
nucleotide – n. 核苷酸
nucleoside – n. 核苷
zalcitabine – n. 扎西他滨
zidovudine – n. 齐多夫定
Test 1. The woman is afraid she may get HIV from her bisexual husband. What should the nurse include when teaching her about preexposure prophylaxis (select all that apply)?
A. Take fluconazole (Diflucan).
B. Take amphotericin B (Fungizone).
C. Use condoms for risk-reducing sexual relations.
D. Take emtricitabine and tenofovir (Truvada) regularly.
E. Have regular HIV testing for herself and her husband.
2. Which strategy can the nurse teach the patient to eliminate the risk of HIV transmission?
A. Using sterile equipment to inject drugs
B. Cleaning equipment used to inject drugs
C. Taking zidovudine (AZT, ZDV, Retrovir) during pregnancy
D. Using latex or polyurethane barriers to cover genitalia during sexual contact
本期ISPN Review答案： 1. C. Use condoms for risk-reducing sexual relations; D. Take emtricitabine and tenofovir (Truvada) regularly; E. Have regular HIV testing for herself and her husband.
Using male or female condoms, having monthly HIV testing for the patient and her husband, and the woman taking emtricitabine and tenofovir regularly has shown to decrease the infection of heterosexual women having sex with a partner who participates in high-risk behavior. Fluconazole and amphotericin B are taken for Candida albicans, Coccidioides immitis, and Cryptococcosus neoformans, which are all opportunistic diseases associate with HIV infection.
2. A. Using sterile equipment to inject drugs.
Access to sterile equipment is an important risk-elimination tactic. Some communities have needle and syringe exchange programs (NSEPs) that provide sterile equipment to users in exchange for used equipment. Cleaning equipment before use is a risk-reducing activity. It decreases the risk when equipment is shared, but it takes time, and a person in drug withdrawal may have difficulty cleaning equipment.
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