Quinidine is almost as powerful an antidote to malaria as quinine; cinchonidine has about two-thirds the power of quinine, and cinchonine less than one-half.

It is stated that incomplete examinations have detected cinchonine in the bark.

The true cinchona barks, containing quinine, quinidine, and cinchonine, are distinguished from the false by their splintery-fibrous texture, the latter being pre-eminently corky.