Cell Wall Synthesis Inhibitors

Question 1

Penicillin types?

Answer 1

Benzylpenicillin, Cloxacillin,

Amoxicillin, Ampicillin

Question 2

Penicillin SOA?

Answer 2

Covers most gram positives

– Spectrum: Amoxicillin > Cloxacillin > Penicillin

Question 3

Penicillin ROA?

Answer 3

Benzylpenicillin (IV), Penicillin V (oral)

Question 4

Amox vs Amp?

Answer 4

Amoxicillin > Ampicillin in terms of oral

bioavailability due to acid stability

Question 5

Penicillin Pharmacokinetics?

Answer 5

Pharmacokinetics: Wide distribution except to CSF

Minimal Hepatic metabolism

Question 6

Penicillin mechanism?

Answer 6

• Bacteriostatic: Inhibit transpeptidase thereby inhibiting the crosslinking of the peptidoglycan in cell wall synthesis
• Bactericidal: Activation of murein hydrolase leading to autolysis of the cell with degradation of the peptidoglycans in the cell wall

Question 7

Penicillin Side Effects & Contraindications?

Answer 7

• Allergy (Rash & Fever)
• Neurotoxicity (rare): Convulsion, Hallucination, Confusion
• aaPMC due to broad spectrum activity

Question 8

Cephalosporins drugs?

Answer 8

Cefalexin, Cefuroxime,

Ceftriaxone, Cefepime

Question 9

Cephalosporins ROA?

Answer 9

IV or IM preparations for 3rd gen beyond

Question 10

Cephalosporins Pharmacokinetics?

Answer 10

Wide distribution and beyond 3rd Gen can penetrate CSF well

Minimal hepatic metabolism

Question 11

Cephalosporins Mechanisms?

Answer 11

• Same as Penicillin

* Resistance evolving due to extended spectrum β lactamases

Question 12

Cephalosporins Side Effects & Contraindications?

Answer 12

• Allergy (Rash & Fever) with crossreactivity with Penicillin
• GIT disturbances with dhiarrhoea
• Thrombophlebitis
• (Ceftriaxone) Forms precipitates in lung and kidney when given with calcium containing agents

Question 13

Carbapenems drugs?

Answer 13

Imipenem, Meropenem

Question 14

Carbapenems SOA?

Answer 14

Broad spectrum as it is even able to penetrate the membrane of even gram negatives

Question 15

Carbapenems Pharmacokinetics?

Answer 15

Pharmacokinetics: Poor oral bioavailability (mainly IV & IM),

Imipenem is broken down in the renal tubules (increase half life by giving with cilastin)

Question 16

Carbapenems Side Effects & Contraindications?

Answer 16

• Allergy (Rash & Fever)
• GIT Toxicity
• Neurotoxicity when overdosed

Question 17

Monobactams drugs?

Answer 17

Aztreonam

Question 18

Why are monobactams safe?

Answer 18

High therapeutic index with low potential toxicity

Question 19

Monobactams Pharmacokinetics?

Answer 19

Pharmokinetics: Only given IV, minimal hepatic

metabolism, 60-70% renal excretion

Question 20

Monobactams MOA?

Answer 20

• Same as penicillin

* Minimal crossreactivity with penicillin

Question 21

Monobactams Side Effects & Contraindications?

Answer 21

• Allergy (Rash & Fever)
• Transaminaemia
• GIT disturbances

Question 22

Vancomycin Spectrum?

Answer 22

Active only against Gram Positives

-Used for clostridium difficile infection in gut

Question 23

Vancomycin Pharmacokinetics?

Answer 23

Given IV with wide distribution (but not CSF), mostly excreted at the kidneys

Question 24

Vancomycin MOA?

Answer 24

• Bind to D-Ala-D-Ala terminal residue on
transpeptidase and prevents both the further synthesis of peptidoglycan and crosslinking

• Rare resistance due to mutations to
transpeptidase (VRSA, VRE)

Question 25

Vancomycin Side Effects & Contraindications?

Answer 25

• Allergy: Red Man Syndrome with a characteristic rash above the nipple line due to histamine release
especially with rapid infusions

• Nephrotoxicity & Ototoxicity especially upon interaction with other agents such as loop diuretics, aminoglycosides, amphotericin B
• Thrombophlebitis

Question 26

Polymyxin ROA?

Answer 26

Parenteral or Topical preparations

Question 27

Polymyxin MOA?

Answer 27

Binds to LPS in the cell wall and causes detergent like damage

Question 28

Polymyxin Side Effects & Contraindications?

Answer 28

Nephrotoxicity