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Pharmacology Exam 2 > Beta Lactam > Flashcards

Beta Lactam Flashcards

1
Q

In Gram + bacteria what is the main barrier for drugs?

A

Bacterial membrane

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2
Q

Main barrier for drugs in Gram -?

A

Outer membrane

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3
Q

Where do beta-lactamases go in Gram +?

A

Extracellular

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4
Q

Where do beta-lactamases go in Gram -?

A

Periplasmic space

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5
Q

Does gram + or gram - have the thicker peptidoglycan?

A

Gram +

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6
Q

How many membranes does Gram + have?

G-?

A

1

2

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7
Q

Besides thickness, what is a difference in structure between G+ and G- peptidoglycan?

A

G- has meso-diaminopimelic acid residue (DAP) while Gram + has L-lysine residue (COOH of DAP replaced by H)

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8
Q

Which bond is Lysozyme sensitive?

A

Beta (1,4)

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9
Q

How is peptidoglycan linked in Gram -?

A

Bridge between DAP residue and terminal D-Ala on different strands

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10
Q

How is peptidoglycan linked in Gram +?

A

Bridge L-Lys and terminal D-Ala

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11
Q

How many amino acids make up the crosslink?

A

5

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12
Q

Mechanism behind B-lactam antibiotics?

A

Inhibition of transpeptidases that glue peptidoglycan together.

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13
Q

With transpeptidase inhibited what kills the cell?

A

Osmotic stress resulting in cell lysis and cell death

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14
Q

What is responsible for reactivity of B-lactam system?

A

Highly strained four membered ring

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15
Q

What is normal bond angle?

A

120

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16
Q

What is compressed bond angle of B-Lactam?

A

90

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17
Q

Why do bacterial transpeptidases not catalyze reactions with host cell proteins?

A

Bacteria have unnatural D-Ala amino acids not recognized in host

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18
Q

What will cause resistance to Beta lactams?

A

Decreased cellular uptake of drug
Mutation of penicillin binding proteins
Efflux pump that pumps drug out

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19
Q

Beta-lactamases do what to neutralize beta lactams?

A

Hydrolyze

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20
Q

What is the spectrum of allergies for beta lactam antibiotics?

A

Drug rash to anaphylactic shock

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21
Q

What do beta-lactams act as to elicit allergic reaction?

A

Haptens

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22
Q

If someone is allergic to one penicillin can they be given another?

A

No

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23
Q

How do you test for an allergy to beta-lactam?

A

Topical flare

Wheal test

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24
Q

Under acidic conditions, main degradation products of Pen G are?

A

Benzylpenicillenic acid
Benzylpenillic Acid
Benzylpenicilloic acid

25
Q

Do penicillin hydrolysis products have any antibiotic activity?

A

No

26
Q

Is hydrolysis of beta-lactam reversible?

A

No

27
Q

Which penicillin is more stable in the stomach?

A

Penicillin V due to electronegativity from extra Oxygen

28
Q

What does the increased electronegativity reduce in beta lactam hydrolysis?

A

Nucelophilicity

29
Q

Ideal pH for penicillins to be stored?

A

6-6.8

30
Q

What catalyzes penicillin degredation reactions?

A

Heavy metal ions

31
Q

Penicillins with more lipophilic side chains are more what?

A

Highly protein bound

32
Q

Protein binding does what?

A

Reduces bioavailability

Protects from degradation

33
Q

How does protein binding effect half lives of penicillin?

A

It doesnt

34
Q

Why does protein binding not effect half life of penicillin?

A

Dissociation rate from protein is fast

Renal excretion rate is rate-limiting

35
Q

Most lipophillic penicillin?

A

Cloxacillin

36
Q

What rapidly excretes penicillins?

A

Kidneys or biliary routes

37
Q

What does most of the work in renal excretion?

A

10% glomerular filtration

90% tubular secretion

38
Q

Kidney disease/failure will cause what?

A

Prolonging of pencillin half life

39
Q

Is penicillin an anion or cation?

A

Anion

40
Q

What are the two mechanisms of tubular secretion for?

A

1 for cations and 1 for anions

41
Q

Why will penicillin treatment combined with probenecid cause an increase in half life?

A

Penicillin will be in competetion with probenecid for tubular secretion via anion mechanism

42
Q

Antimicrobial spectrum for Pen G?

A

Gram + cocci,
Neisseria gonorrhoeae
Haemophilus influenzae

43
Q

Most effective route of Pen G administration?

A

Parenteral

44
Q

Why is methicillin beta lactamase resistant?

A

Steric hindrance protects it from nucelophilic attack

45
Q

Why must methicillin be injected?

A

Stomach pH makes its half life go to about 5 minutes

46
Q

Antimicrobial spectrum for methicillin?

A

Narrow, mainly for staph aureus

47
Q

Why is methacillin resistant staph aureus resistant to methicillin?

A

Mutation in penicillin binding protein

48
Q

Name of the penicillin binding protein that methicillin resistance gene codes for?

A

PBP2

49
Q

Difference between Cephapirin and penicillin

A

Six membered sulfur containing ring fused to beta lactam instead of five membered ring

50
Q

What inactives the Cephapirin?

A

Host esterases via acetate in 3-postion

51
Q

Difference between penicillin and imipenem?

A

Sulfur in thiazolidine ring replaced by methylene group

52
Q

What is the result of the ring change between penicillin and Imipenem?

A

Reactivity increased in Imipenem due to greater ring strain

53
Q

What does imipenem do to beta lactamases?

A

Inhibits them

54
Q

What hydrolyzes imipenem?

A

renal dehydropeptodase-1

55
Q

How do you stop the hydrolyzing of imipenem?

A

Co-administer with dehydropeptidase-1 inhibitor cilastatin

56
Q

Combination with larger spectrum than anything else in U.S?

A

Imipenem with cilastatin (G+ and G-)

57
Q

How is imipenem-cilastatin administered?

A

Parenterally

58
Q

Antibiotic spectrum of Aztreonam?

A

G-

Pharmacology Exam 2 (9 decks)

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