Urinary antiseptics are drugs which exert antibacterial activity only in the urinary tract (and no systemic activity).They include nitrofurantoin and methenamine mandelate.

Urinary  tract  infection (UTI)

Symptoms of UTI

• Pain or discomfort  when peeing[ or burning  with urination]
• Sudden urges to pee
• A need to pee more often than usual [ frequent  urination]
• Feeling as though you’re  unable to empty your bladder fully
• Also Painis present  low down in your tummy
• Feeling generally unwell ,achy, and tired
• Blood in urine[  which is knows as hematuria]
• Urine that smells bad or looks cloudy

Infection of the urinary tract is quite common and may be acute or chronic.

Causes of UTI

• Dehydration
• Holding pee
• Constipation
• Kidney stones
• Uncontrolled diabetes ( sugar)
• Many bacterial infections

Many drugs are uses to treatment  of UTI caused by bacteria, which exert antibacterial  activity. Moreover antibacterial  activity  are two types…..

• Bacterostatic( or inhibition of growth of  bacteria )
• Bactericidal (or killing to bacteria)

Drugs which are uses in treatment of UTI for examples

• Urinary  antiseptics like NITROFURANTOIN  and METHENAMINE MANDELATE

• SULFONAMIDES

• cotrimoxazole,

• nalidixic acid,

• fluoroquinolones,

• ampicillin,

• cloxacillin,

• carbenicillin,

• aminoglycosides,

• tetracyclines and

• cephalosporins

Secondly Some drugs also have analgesic or pain reliever  action  on the urinary tract ,knows as urinary analgesic, these are

• PHENAZPPYIDINE-an azo dye, has analgesic actions on the urinary tract (not an antibacterial actions ) and relieves burning symptoms of dysuria and urgency in cystitis and UTI. It can cause nausea and gastric irritation. It colours the urine orange red.

         Dose: 200–400 mg TDS, PYRIDIUM 200 mg tab.

NITROFURANTOIN

Nitrofurantoin is a synthetic nitrofuran which is bacteriostatic, but at higher concentrations, it may be bactericidal. Likewise, It is effective against many gram-positive and gram-negative bacteria.

 Mechanisms  of actions

Nitrofurantoin is rapidly reduced by the bacteria to highly reactive derivatives which damage DNA and affect DNA and RNA synthesis. Since human cells require a long time to reduce nitrofurantoin, toxicity is not significant. Moreover, the development of resistance is slow. It is rapidly and completely absorbed from the gut. Plasma t½ is 0.3–1 hr; attains high concentration in the urine.

Side effects

• Nitrofurantoin may cause nausea,vomiting,diarrhoea, allergic reactions and rarely chronic-active hepatitis.
• As wll as Haemolytic anaemia can occur in G6PD deficient individuals.
• Nitrofurantoin  also turns the urine dark brown by its metabolites.
• Pneumonitis and interstitial pulmonary fibrosis may occur after long term which may be due to generation of oxygen radicals in the lung.
• Long-term treatment can also result in neurological disorders due to the formation of toxic metabolites in the body.

Dose: 50–100 mg 6 hrly, FURADANTIN 50, 100 mg tab 25 mg/5 ml susp.

Uses

1.  If the microorganisms  are found to be sensitive to nitrofurantoin  so it is an useful alternative  in acute UTI. Since alkalinity of the urine can reduce the antimicrobial activity, acidification of urine with ascorbic acid or other organic acids is useful.

2. Long-term suppression of chronic UTI (single dose 100 mg at bedtime) and for prophylaxis of UTI.

 

Methenamine Mandelate

Methenamine (hexamine) mandelate, a salt of mandelic acid and methenamine, releases formaldehyde in acidic urine below pH 5.5. Formaldehyde is bactericidal and resistance does not develop to it. Acidic pH of the urine should be maintained by using ascorbic acid, mandelic acid or hippuric acid. In addition, Acidic pH itself is bacteriostatic—an added advantage of maintaining low pH. Also,Urea splitting microorganisms like proteus may counter the effects of methenamine by raising the urinary pH. Hence, it is important to keep a watch on urinary pH for such organisms. Mostly , E. coli and gram-negative bacteria are suppressed by methenamine mandelate.

Dose: 1 g 3–4 times a day. MANDELAMINE 0.5 g,1 g tab.

Side effects

• High doses can cause nausea and epigastric distress due to release of formaldehyde in the stomach—given as enteric-coated tablets to prevent this.
• Long-term use can cause haematuria, chemical cystitis and also painful micturition.
• Methenamine mandelate should be avoided in case of  renal failure as mandelic acid adds to acidosis.

Drug interactions:

Methenamine binds sulfonamides and neutralises their action. Also, sulfonamides are precipitated in the acidic urine. Hence, the combination should be avoided.

Uses

Methenamine mandelate is used orally in chronic UTI that is resistant to other drugs.