Just as wine vintages vary, so the weather can affect the number of harvests a coca plant yields and the alkaloid content of the leaves.

ECONOMIST: Coca and cocaine in the Andes

D. in biochemistry from the University of Minnesota, Heinicke has staked his reputation on an alkaloid he calls xeronine that allegedly opens cell membranes to admit greater amounts of amino acids.

FORBES: Tale of the South Pacific

This releases an alkaloid in the leaf.

BBC: Transcript: Cocaine: Alex James in Colombia