Drugs

Question 1

Metronidazole as a codrug in empiric therapy

Answer 1

Why Metronidazole is used as a Codrug?

1. Anaerobic Coverage:

Metronidazole is highly effective against obligate anaerobes (e.g., Bacteroides fragilis, Clostridium spp.).

It complements drugs that lack anaerobic activity (e.g., cephalosporins, aminoglycosides)
2. Synergistic Use:
Often combined with other broad-spectrum antibiotics (like ceftriaxone, ciprofloxacin, or piperacillin-tazobactam) for broader pathogen coverage.
Especially valuable in intra-abdominal infections, pelvic infections, aspiration pneumonia, and dental infections.
3. Cost-Effective and Oral/IV Options:

Available both orally and intravenously, allowing flexibility in treatment.

Question 2

Metronidazole as a codrug in empiric therapy

Answer 2

Common Clinical Scenarios for Empiric Use:
1-Aspiration pneumonia
2-Brain abscess
3-Pelvic inflammatory disease
4-protozoal infections.
5-Clostridioides difficile infection (though vancomycin or fidaxomicin is now first-line)
6-Colorectal surgical prophylaxis
7-H.pyloriTreatment
8-Intra-abdominal infections (e.g., perforated appendicitis, diverticulitis)

Question 3

Benzimidazoles

Answer 3

*Benzimidazoles are a class of antiparasitic and antifungal. *Mode of action:
disrupting microtubule formation in parasites and fungi as it bind to β-tubulin, preventing polymerization into microtubules.
*This impairs:
-Glucose uptake → energy depletion
-Cell division and intracellular transport leading to parasite death

Question 4

Benzimidazoles

Answer 4

1-Albendazole Broad-spectrum anthelmintic Binds to β-tubulin → inhibits microtubule formation
2-Mebendazole…معدة
Intestinal helminths (e.g., Ascaris, Trichuris) Same as albendazole
3-Thiabendazole Less commonly used; strongyloidiasis Inhibits fumarate reductase (also disrupts microtubules)
4-Fenbendazole Veterinary use Similar mechanism; effective against nematodes
5-Flubendazole Mainly veterinary; some human use Similar to mebendazole

Question 5

Albendazole-specific uses

Answer 5

تحشيشة ACE
A – Ascaris and other nematodes

C – Cysticercosis (Neurocysticercosis)

E – Echinococcus (Hydatid disease

Question 6

Nematodes treated with benzimidazoles

Answer 6

Mnemonic: “NEAT Worms” –

N – Necator americanus (hookworm)

E – Enterobius vermicularis (pinworm)

A – Ascaris lumbricoides

T – Trichuris trichiura

Question 7

Ivermectin (Mech. of action, indication, dose)

Answer 7

1-Mechanism of action
Acts as anti - parasite by acting on GABA “Gamma Amino Butyric Acid” receptors of parasite leading to incease chloride ion influx leading to
Hyperpolarization leading to
Paralysis of worm
2-Indications
* Strongyloides : main line of treatment
* Filariasis : used with DEC or Albendazole
* Scabies
* Pediculus Capitis
* Ascaris
3-Dose
In sacbies:200mcg/kg single dose and reapated after 1-2 weeks