Exam 1- Cushman Lecture 2- Cephamycins + Carbapenems Flashcards
What functional group is unique to the cephamycins?
7a-methoxyl group (OCH3)
What is the function of the 7a-methoxyl group in cephamycins?
Increases stability against B-lactamases
What is the main cephamycin drug?
Cefotetan
What should patients be counseled on with cephamycins?
Do not drink alcohol with them
What are the 2 carbapenems?
Iminipenem
Thienamycin
Why can thienamycin NOT BE USED AS A DRUG?
It is too reactive
-the primary amino group attacks the B-lactam intermolecularly
*Imipenem is a derivative
How has the reactivity of thienamycin been overcome in its derivative, imipenem?
Addition of an N-formiminoyl group prevents intramolecular attacks from the primary amino group
How does the structure of carbapenems differ from penicillins?
The sulfur present in the thiazolidine ring of penicillins is replaced by a methylene group
What affect does the methylene group in the carbapenem structure have?
Increases reactivity because methylene is smaller then sulfur, so the ring strain is greater in carbapenems
What unique function does imipenem have?
It also reacts with and inhibits B-lactamases, not just penicillin-binding proteins
Imipenem is hydrolyzed by what?
renal dehydropeptidase-1
How can Imipenem hydrolyzation by renal dehydropeptidase-1 be overcome?
with co-administration of the dehydropeptidase-1 inhibitor: Cilastatin
*coadministration gives these drugs broad-spectrum activity (active against both Gram + and -)
Which drug class is referred to as the “magic bullets” due to their broad spectrum activity?
Carbapenems (imipenem)
What drug is a monobactam?
Aztreonam disodium
*synthetic
How are monobactams able to be active without a carboxylic acid group?
A sulfamic acid group takes its place (SOOON)
*this differs from penicillins and cephalosporins that have carboxylic acid groups
