Urinary Antiseptic

Urinary Antiseptics

Urinary antiseptics concentrate in the urinary tract to produce an antimicrobial effect without producing systemic antimicrobial effects. Thus they are used to treat urinary tract infection without any serious adverse effects. Following pathogens cause Urinary tract infection (UTI):

·         Escherichia coli (E. coli). 80% of uncomplicated upper and lower urinary tract infection is due to E. coli.

·         Staphylococcus saprophyticous. 10% to 15% of UTI is due to S. saprophyticous.

·         Klebsiella pneumonia

·         Proteus mirabilis

There are several factors that may develop UTI in women such as frequent sexual intercourse, lack of urination after sexual intercourse, the unhygienic condition of the external urinary part, use of a diaphragm, use of spermicidal cream, use of an unhygienic public toilet, UTI recurrent history.

Urine is itself antiseptic. It resists UTI infection. But UTI may occur at any age. Childbearing age and elderly women are more prone to UTI than men due to urinary tract anatomy. Longer urethra in male resists microbial flow into urethra and bladder. However, the male also suffers from UTI. 

 

Urine plays important role in bacterial growth inside urinary tract. Alkaline or neutral urine promote bacterial growth. While acidic urine promotes E. coli growth. There are two types of UTI.

·         Upper urinary tract infection that causes acute pyelonephritis and

·         Lower urinary tract infection that causes urethritis, cystitis, and prostatitis.

In urinary tract infection, only one or both may develop. Lower urinary tract infection can be treated with a low dose of the drug and short duration of treatment. Upper urinary tract infection treatment requires a high dose of a drug for a longer duration.

Urinary antiseptics produce an antimicrobial effect in the urinary tract. They have little or no systemic antimicrobial effect. Various systemic antimicrobial agents are excreted unchanged in urine. They also act as a urinary antiseptic in low dose. 

Thus two categories of drugs are used to treat UTI:

• §  Urinary Antiseptic
• §  Systemic antimicrobial agents in low dose

URINARY ANTISEPTICS

·  Nitrofurantoin: Nitrofurantoin is a narrow spectrum antimicrobial agent. It acts as bacteriostatic and very effective against E. coli. It shows highest antimicrobial activity in acidic urine. However, its effectiveness is less than antibiotics to eradicate UTI.

Mechanism of Action: Nitrofurantoin sensitive bacteria reduce Nitrofurantoin to active metabolites by an enzymatic reaction. These metabolites damage bacterial DNA to produce a bacteriostatic effect.

Pharmacokinetics: It is rapidly absorbed from the intestine and rapidly excreted in urine. It is not detected in plasma in recommended dose for UTI. It changes the color of urine to brown. It is administered with milk or food do to avoid GIT side effects. It should not be used in renal insufficiency and in glucose-6-phosphate dehydrogenase insufficiency.

Adverse Effects: GIT disturbance, nausea vomiting, and diarrhea. Acute pneumonitis as interstitial pulmonary fibrosis. Neurological complications like a headache, vertigo, drowsiness and muscular ache.

Methenamine: It decomposes slowly in acidic urine to form formaldehyde. It takes 3 hours for 90% decomposition. Formaldehyde is toxic to most of the bacteria. Bacteria do not develop resistance to formaldehyde.

It is administered orally with mandelic acid and hippuric acid. Both are weak acid that lowers urine pH. However, mandelic acid also acts as a urinary antiseptic.

Pharmacokinetics: It decomposes in acidic media. Thus it is administered as an enteric-coated tablet to prevent degradation in the stomach. It is contraindicated in hepatic insufficiency because it also produces ammonia during metabolism in the liver.

        SYSTEMIC ANTIMICROBIAL AGENTS TO TREAT UTI: 
        
           Various systemic antimicrobial agents in low dose are used as a urinary antiseptic to treat UTI.

              Ex.

·         Quinolones such as nalidixic acid, ciprofloxacin, norfloxacin,

·         Ciphalosporine,

·         Aminoglycosides

·         Sulphonamides

·         Trimethoprim

·         Sylphonamide and trimethoprim combination.

UTI Treatment

Lower Urinary Tract Infection:

·    One Day Therapy: Acute uncomplicated cystitis can be treated by using a single dose of 4 to 6 cotrimoxazole or 400mg of trimethoprim or 3 gm of sulfamethoxazole or 3 gm of amoxicillin. Amoxycilline is less effective among three antimicrobial drugs. Single dose treatment is used to treat UTI not more than 10 days old.

·         Three Days Therapy: It is more effective with fewer side effects than one day therapy. It is recommended for uncomplicated UTI.

·         Seven Days Therapy: Usually three days therapy is preferred to treat UTI. UTI in women suffering from pyelonephritis, diabetes or urologic disorder, UTI symptoms for more than 10 days, use of a diaphragm, age above 65 years is considered as complicated UTI. It needs seven days therapy.

UTI in Male suffering from urologic abnormalities or prostatitis is also treated by using seven days therapy.

Upper Urinary Tract Infection: In most cases, pyelonephritis is due to E. coli. 10 days antimicrobial therapy will be required to treat upper urinary tract infection. Ex. Cotrimoxazole, trimethoprim alone, aminoglycosides, cephalosporin, doxycycline etc are used. In recurrence treatment requires 2 to 6 weeks antimicrobial therapy. Usually, recurrence occurs due to any other urinary disease.

UTI during pregnancy: Amoxycilline, nitrofurantoin, or cephalosporin are used in acute cystitis due to UTI during pregnancy. Acute pyelonephritis requires hospitalization and parenteral administration of cephalosporin or any other broad-spectrum antibiotics.

Recurrent UTI: Early recurrence may occur in upper UTI. It may be due to incomplete eradication of UTI or vaginal colonization of pathogens. Recurrence after 14 days may be due to reinfection.

Pyelonephritis: It is inflammation of the kidney, mainly due to a bacterial infection.

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