It is directly proportional to the total amount of unchanged drug that reaches the systemic circulation.

它直接与到达体循环的原形总药量成正比。

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The drug exits the body unchanged in the urine.

药物以原形随尿排出。

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For drugs excreted primarily unchanged in urine, bioavailability can be estimated by measuring the total amount of drug excreted after a single dose.

对那些以原形经尿排出为主的药物而言，其生物利用度可以通过测量单次用药后尿药总量来评估。

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The US Department of Justice said in reaction to the vote that its drug enforcement measures would remain unchanged.

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The time required for the FDA to review the data on and approve a new drug--about 18 months--has been essentially unchanged for the past decade, while the duration of clinical testing (largely a function of FDA requirements) has gradually increased.

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