有些药品为什么规定有效期?根据什么规定的?有效期怎样计算?清列出规定有效期药品的品种和它们有效期的具体规定。答:有些稳定性较差的药品,在贮存中间,药效可能降低,毒性可能增高,有的甚至不能供药用。为了保证用药的安全、有效,对这类药品必须规定有效期,即在一定贮存条件下能够保持质量的期限。药品的有效期应该根据药品稳定性的不同,通过留样观察实验,合理制订。药品新产品的有效期,可 Why do some drugs provide for the expiration date? According to what the provisions of the expiration date? Clear out the expiration date of the varieties of drugs and their specific provisions. A: Some drugs with poor stability may lower their potency and may increase their toxicity when stored. Some of them may not even be available for medical use. In order to ensure the safety and effectiveness of the medication, the expiration date of such drugs must be stipulated, that is, the time limit for maintaining the quality under certain storage conditions. Validity of the drug should be based on the stability of different drugs, through the sample observation experiment, rational development. Validity of new drug products may be