The H2 antagonist burimamide showed poor bioavailability inclinical trials.
(i) Define the term bioavailability. In your answer, distinguishbioavailablility
from bioactivity.
(ii) Protonation of the imidazole ring was identified as a reasonfor the low
bioavailability of burimamide. Explain, using appropriatestructures, why
thiaburimamide, which features a sulfur atom in the alkyl chain,led to
increased bioavailability.
(iii) Thiaburimamide, also led to a modest increase inbioactivity. Propose a
reason for this increase in activity.
