Because LD needs long term treatment, the anti-infection substances we use have very low toxicity that can be used for long term. Pharmacologically, the toxicity of the any medicinal substance is measured by LD50 ( LD 50 is the dose of the substance sufficient to kill 50% of a test population of animals within a certain time frame, it is an indicator of the toxicity of a substance) and the safety is measured by therapeutic index (LD50/ED50 (ED 50 is the dose of the substance sufficient to have intended effects in 50% of a test population of animals within a certain time frame, it is an indicator of the efficacy of a substance).)When we choice the substances, their safety level is first concern. For example, the main anti-infection substance Allicin (Allitridi) Capsule, its therapeutic index is 67.45 ~ 134.9 that means while use 67.45 ~ 134.9 times of the daily dose will show toxicity. Its LD50 is 134.9 mg/kg; 67.45 ~134.9 times higher than the therapeutic dose (2 mg/kg ~1 mg/kg per day). Its long term use accumulative toxicity has also been studied. Because it has a very short half-life time in the body and can quickly eliminate from the body, there will be no accumulative toxicity.
The therapeutic index for artemisinin is 36.8 and comparatively chloroquine is 28.8. We use artesunate which is a molecular modified derivative of artemisinin that has better therapeutic index than artemisinin. Other anti-infection substances we use all have therapeutic indexes checked to ensure their long-term use safety.