A polymorph is an alternate physical form of a compound.

The change in physical form may impact the finished product in a number of ways;

• A structure change may lead to a different therapeutic impact or may not be therapeutically viable in the same way may also have “off target” effects.

• It may have an alternate crystal structure / shape which could impact flow and properties such as particle size which may have impact on manufacturing processes or bioavailability

A ratio that compares the blood concentration at which a drug becomes toxic and the concentration at which the drug is effective.

The larger the therapeutic index (TI), the safer the drug is. If the TI is small (the difference between the two concentrations is very small), the drug must be dosed carefully and extra care taken w.r.t mix ups and dispensing of the AS or any OOT results.