Drug Stability

Question 1

Despite the toxicity of curare the hunters were still able to eat the key of the animals killed by it, Expain.

Answer 1

• tubocurarine is a major component of curare which is a neuromuscular blocker
• when used in hunting it paralyses the animal eventually resulting death by asphyxiation
• the drug is not destroyed on cooking but the meat can be eaten
• because tubocurarine cannot cross the gut membrane by passive diffusion therefore it is not absorbed and doesn’t accumulate in the blood stream
• because the drug is a quaternary ammonium compound ionised at all values of pH
• and a tertiary amine which will exist predominantly as the cation at gut pH
• also a phenol but phenols are normally too weakly acidic to ionise the range of pH values found in the body

Question 2

Under what conditions are ester contain drugs stored and why?

Answer 2

• stored in an airtight container to prevent access to moisture
• because ester groups are prone to acid and base catalysed hydrolysis