URINARY ANTISEPTICS

URINARY ANTISEPTICS

• Oral drugs rapidly excreted via urine.
• Suppresses bacterial growth in urinary tract.
• More effective in acidic urine, – Due to low pH being an independent bacterial growth inhibitor.

Important urinary antiseptics:

• Nitrofurantoin, methenamine mandelate & nalidixic acid.

Individual drug description:

1. Nitrofurantoin:

• Active against most urinary pathogens, except Pseudomonas & Proteus.
• Develops slow resistance.
• Used infrequently.

MOA: 

• Allows bacterial enzymes to act itself –> results in reduction of nitrofurantoin –> DNA damage.

Adverse effects: 

• Diarrhea, phototoxicity, neurotoxicity, peripheral neuropathy & hemolysis in G-6-PD deficient patients.

2. Methenamine Mandelate:

• Mandelate salt is used – Itself a urine acidifying agent.
• Ineffective against Proteus – Due to NH release –> alkalinizing urine.

MOA:

• Methenamine release formaldehyde at low pH (below 5.5).
• Formaldehyde contributes to its antibacterial activity.

Contraindication:

• Combination with sulfonamides.
• Due to insoluble complex formation between formaldehyde & sulfonamides.

3. Nalidixic acid:

• A quinolone drug.

MOA:  

• Acts by inhibiting DNA gyrase.
• Ineffective against pseudomonas & proteus.
• Resistance emerges rapidly.

Adverse effect:

• Neurotoxicity (major).

NOTE:

• Phenazopyridine:
• Has analgesic property & useful for alleviating symptoms of dysuria, frequency, burning & urgency.
• Not a urinary antiseptic.

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