TYK157: Difference between revisions
No edit summary |
m Text replacement - "<p style="text-align: center;"> About Test Your Knowledge</p>" to "<p style="text-align: center;"> About Test Your Knowledge</p> Category:TYK" |
||
| (One intermediate revision by the same user not shown) | |||
| Line 42: | Line 42: | ||
<p style="text-align: center;">[[TYK156|<Prev Question]] --- [[TYK158|Next Question>]]</p> | <p style="text-align: center;">[[TYK156|<Prev Question]] --- [[TYK158|Next Question>]]</p> | ||
<p style="text-align: center;">[[TYK About | About Test Your Knowledge]]</p> | <p style="text-align: center;">[[TYK About | About Test Your Knowledge]]</p> | ||
[[Category:TYK]] | |||
Latest revision as of 02:49, 25 September 2026
A pharmaceutical company is testing four new drugs in the same class; all are weak acids. Which of the following is likely to have the most rapid onset of action at physiologic pH?
a) pKa = 3
b) pKa = 5
c) pKa = 7
d) pKa = 9
Click for Answer
Answer
Answer d.
Weak acids may exist as either A- or as HA species. Based on the Henderson-Hasselbalch equation, a weak acid with a pKa above the present pH would be more likely to be found in the non-ionized HA form (and thus cross membranes and have a shorter onset of action) than one with a pKa below pH. Thus, a drug with pKa of 9 would have the fastest onset at physiologic pH (7.4) of the available choices.
Notes
- This question originally printed in the Pediatric Anesthesiology Review Topics kindle book series, and appears courtesy of Naerthwyn Press, LLC.
Keywords