• Question: Which out of efficacy, dosage and toxicity are the most important when testing the safeness of drugs

    Asked by calvinjohnson2 to Rachel on 7 Jun 2019.
    • Photo: Rachel Hardy

      Rachel Hardy answered on 7 Jun 2019:


      Hey, great question 🙂 ! All 3 of these are extremely important factors that need to be considered when developing a new drug. However, toxicity and dosage are most important when referring to the safety of drugs. The ‘toxicity’ of a drug refers to any bad or ‘toxic’ effect that the drug causes (these effects may involve any organ in the body, but are most commonly associated with the heart and liver). For example, a drug may cause a decrease in the ability of the heart to pump blood effectively. Usually, the benefit vs risk profile of a drug is considered when making a decision whether or not to continue developing a drug. If a drug is likely to kill someone or make them seriously unwell, it will not be taken any further. However, if a drug is likely to cause some bad side-effects, but is the best treatment available for a certain disease (e.g. a new drug to increase the survival time of a terminal cancer), this may still be considered. The dose of a drug is strongly linked with its toxicity. Any drug given at too high a dose will likely result in toxic effects in patients. When new drug is being developed, scientists in the lab aim to find out what dose of a drug is toxic, and what dose of a drug is needed for it to be effective. Obviously we can’t give drugs at a certain dose if they will be toxic, but they also still need to be given in a dose which can treat the disease.

      I hope this helps to answer your question. Efficacy is still an important consideration after drug safety testing. This basically refers to how effective the drug is at treating the disease. If the results of safety testing show that the drug is safe in a low dose, but this dose is not effective, there is no point developing it further. The whole drug discovery process is often a delicate balance of efficacy vs toxicity 🙂

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