Miscellaneous And Urinary Antiseptics (metro and nitro)

Question 1

First drug to discuss in this category is metronidazole. What is the MOA of this drug?

Answer 1

Imidazole derivative – activity against protozoa and bacteria

• -activity is dependent on anaerobic conditions as it undergoes a reductive bio-activation of its nitro group by ferredoxin.
• -forms reactive cytotoxic products that interfere with nucleic acid synthesis.

Question 2

What is the spectrum of activity and clinical applications of metronidazole?

Answer 2

Anaerobes (bacteriodes and clostridium)
Tx:
–of anaerobic or mixed intra-abdominal infections, vaginitis (trichomonas, vaginosis) and brain abscesses (alot of times in combo with the other anaerobe abx clindamycin)

Question 3

Metronidazole is the drug of choice for what?

Answer 3

Tx of C. difficile infections

Question 4

In combo with other drugs, metro can be used in the eradication of what?

Answer 4

H. pylori

Question 5

As an antiprotozoal drug, metro is the drug of choice in what infections?

Answer 5

Trich
Giardiasis
Tx of intestinal amebiasis and amebic hepatic abscesses

Question 6

What are the pharmacokinetics for metronidazole?

Answer 6

Oral, IV, rectally, or topically (vaginal gel)
Widely distributed and penetrates well into the CSF and brain
Metabolized in the liver and may accumulate in hepatic insufficiency

Question 7

What are the adverse effects of metronidazole?

Answer 7

1. Prolonged use: n/d and peripheral neuropathy
2. Disulfram like effects: avoid in alcoholics
3. Opportunistic fungal infections
4. Dark coloration of the urine

Question 8

What are the contraindications of metronidazole?

Answer 8

Pregnancy: avoided during 1st trimester

Question 9

The last drug is a urinary antiseptic, Nitrofurantoin. What is the MOA?

Answer 9

Rapidly secreted into the urine — acts to suppress bacteriuria
No systemic effects
Formation of reactive intermediates that damage bacterial DNA
No cross-resistance with other drugs and the emergency of resistance to nitro is very slow

Question 10

What is the spectrum of activity and clinical applications?

Answer 10

Bacteriostatic and Bactericidal 
Gram + and Gram - 
P. aeruginosa and Proteus = resistant 
Use: 
prophylaxis and treatment of lower UTIs 
(nitro is a good alternative oral agent for the tx of UTIs)

Question 11

What are the pharmacokinetics for nitro?

Answer 11

Metabolized and excreted rapidly – so no systemic antibacterial action

Question 12

Finally what are the adverse effects and contraindications of nitro?

Answer 12

Anorexia, Nausea and Vomiting
Rare: neuropathies and hemolytic anemia
Contraindications:
pregnancy at term (38-42 weeks) and infants less than one month old
Renal insufficiency: due to accumulation of drug