Receptor theory of Analgesics

Question 1

What is the hypothesis for the firs theory called?

Answer 1

Beckett-Casy hypothesis

Question 2

What is the hypothesis involving Nitrogen?

Answer 2

There must be a basic centre (Tertiary N-methyl) which has a 50% of being ionized or non-ionized at physiological pH. The unionized form can cross the BBB, and the ionized form will bind at the receptor site.

Question 3

What should the pKa for the 50% chance of ionized/non-ionized form Nitrogen be?

Answer 3

The pKa needs to be between 7.8 - 8.9 for an equal chance.

Question 4

What is the hypothesis involving the aromatic ring?

Answer 4

The top aromatic ring is essential for activity and must be properly orientated with respect to the ntrogen atom to allow Van Der Waals interactions of the ring with the receptor

Question 5

What is the hypothesis involving the phenol group?

Answer 5

The phenol group is probably hydrogen-bonded to a suitable residue at the receptor site - one of the amino acids

Question 6

What is the hypothesis involving the ethylene bridge?

Answer 6

There must be a hollow ring for the ethylene bridge to form between the Tertiary Nitrogen and a carbon.