Penicillin I

Question 1

What was the first penicillin with anti-pseudomonal properties?

Answer 1

carbenicillin

Question 2

What is a popular penicillin combination drug in use in hospitals today (trade name Zosyn)?

Answer 2

piperacillin and tazobactam

Question 3

Augmentin contains a combination of…

Answer 3

amoxicillin and clavulanic acid

Question 4

What are six characteristics of the ideal penicillin?

Answer 4

stability at low pH (ie in the stomach), slower renal elimination, stability against beta lactamases, broader antimicrobial coverage, better penetration into CSF, no hypersensitivity reactions

Question 5

What is the half-life of most penicillins?

Answer 5

2 hours

Question 6

Which renal filtration method contributes more to the elimination of beta lactams, glomerular filtration or tubular secretion?

Answer 6

glomerular filtration

Question 7

Penicillin G is mostly active against gram ______ organisms

Answer 7

positive

Question 8

Penicillin G is also known as….

Answer 8

benzylpenicillin

Question 9

What organisms does Penicillin G have good activity against?

Answer 9

group A streptococcus, group B streptococcus (ex.: S. agalactiae), S. viridans, S. pneumoniae (although resistance increasing)

Question 10

What organisms does Penicillin G have moderate activity against?

Answer 10

enterococci gram negative aerobes

Question 11

Penicillin G is a drug given _______

Answer 11

intravenously

Question 12

Which aqueous salt form of Penicillin G is most commonly dispensed?

Answer 12

potassium (Penicillin GK)

Question 13

How many milliequivalents of potassium are present per million units of Penicillin GK given?

Answer 13

1.7 mEq

Question 14

Too much potassium can cause what major health problem?

Answer 14

cardiac arrest

Question 15

How often must Penicillin GK be given for serious infections and why?

Answer 15

every 4 hours, because it is quickly eliminated

Question 16

How many million units per day of Penicillin GK is considered a high dose?

Answer 16

24 MU

Question 17

Which two formulations of Penicillin G are suspensions and only suitable for intramuscular injection?

Answer 17

Procaine Penicillin G, Benzathine Penicillin G

Question 18

Which Penicillin G suspension is not used much anymore because of hypersensitivity issues?

Answer 18

Procaine Penicillin G

Question 19

Which Penicillin G suspension is very long-acting?

Answer 19

Benzathine Penicillin G

Question 20

Why is Benzathine Penicillin G so long acting?

Answer 20

it deposites a reservoir of drug in the muscle that must slowly diffuse into the blood, so only a little penicillin leaks into the blood at a time

Question 21

What is Benzathine Penicillin G effective in treating?

Answer 21

all stages of syphillis, prophylaxis for rheumatic fever, sometimes Strep pharyngitis

Question 22

What is the formulation of Penicillin G meant to be used as an oral dose?

Answer 22

Penicillin V

Question 23

What makes Penicillin V effective as an oral dose?

Answer 23

it is designed to resist acid hydrolysis (like in the stomach), so oral bioavailability much higher

Question 24

Is it better to take Pencillin V on an empty stomach (1 hour before or 2 hours after meals) or with food?

Answer 24

on an empty stomach

Question 25

Which compound, although not a penicillin, is usually taken with penicillin V because it increases the bioavailability?

Answer 25

probenecid (benemid)

Question 26

How does probenecid increase the bioavailability of Penicillin V?

Answer 26

it blocks selective tubular secretion of pencillins, increasing their half-lives

Question 27

When should you take probenecid?

Answer 27

30 minutes before antibiotic

Question 28

Where does selective tubular secretion take place in the kidneys?

Answer 28

peritubular capillaries

Question 29

What percentage of people who take penicillins exhibit hypersensitivity reactions?

Answer 29

10%

Question 30

What percentage of people "outgrow" their penicillin allergy (do not have a reaction after taking penicillin at least 10 years after their initial reaction)?

Answer 30

80%

Question 31

What is the difference between hives and flat, blotchy rashes?

Answer 31

hives are raised bumps, happen almost immediately and progressively get worse; flat, blotchy rashes not raised, may not occur until several days after starting therapy (of less concern)

Question 32

What Pregnancy Risk Factor are penicillins placed in and how does it affect therapy in pregnant patients?

Answer 32

Pregnancy category B, probably safe to use in pregancy (low risk)

Question 33

What three pregnancy categories indicate drugs that should NOT be used in pregnant patients without very good reason?

Answer 33

pregnancy category C, D, X

Question 34

Anti-staphylococcal penicillins are also called __________

Answer 34

penicillinase-resistant penicillins

Question 35

What is the preferred anti-staphylococcal penicillin in use today (not active against MRSA)?

Answer 35

nafcillin

Question 36

Why is methicillin no longer used in treatment?

Answer 36

issues with interstitial nephritis

Question 37

Methicillin and Nafcillin are only useful as ________ agents because of their poor absorption from the GI tract.

Answer 37

parenteral

Question 38

What is unique about the elimination of anti-staphylococcal penicillins?

Answer 38

they are eliminated primarily through the renal pathways but also through the biliary pathway, therefore the dose doesn't need to be adjusted in patients with renal failure; the liver sends the drug into the biliary duct which drains into the intestine

Question 39

What is the class of anti-staphylococcal penicillins designed for oral dosing?

Answer 39

isoxazolyl penicillins

Question 40

Which anti-staphylococcal penicillin is available as an IV, IM, and oral dose?

Answer 40

oxacillin

Question 41

Why can isoxazolyl penicillins be dosed orally?

Answer 41

they are specifically designed to resist acid hydrolysis

Question 42

What differentiates cloxacillin and dicloxacillin from oxacillin?

Answer 42

cloxacillin/dicloxacillin only available as oral doses, have chlorine groups (1 in cloxacillin, 2 in dicloxacillin) added to them which dramatically increases bioavailability

Question 43

What three additional organisms (besides those already covered by Penicillin G) does ampicillin cover?

Answer 43

escherichia coli, haemophilus influenzae, proteus mirabilis

Question 44

What are two aminopenicillins?

Answer 44

ampicillin, amoxicillin

Question 45

Of the aminopenicillins, _______ is available in IV, IM, and oral doses, while _________ is only available as an oral dose.

Answer 45

ampicillin, amoxicillin