Pharmacology for Dentistry

314 Section 9/ Chemotherapy

Other adverse effects include superin-

fection, hepatotoxicity and typhoid shock.

Therapeutic Uses

Because of bone marrow toxicity of

chloramphenicol, its use is restricted to the

treatment of infection caused by S. typhi and

paratyphi (treatment of typhoid fever).

Other indications in which chlorampheni-

col can be used are H. influenzae meningitis,

urinary tract infections, anaerobic infections

caused by Bacteroides fragilis and locally in eye

and external ear infections.

CHEMOTHERAPY OF URINARY

TRACT INFECTIONS

URINARY ANTISEPTICS

Urinary antiseptics are orally administered

agents that exert antibacterial activity in the

urine but have no systemic antibacterial

activity. Urinary antiseptics are listed as in

table 9.2.2.

NITROFURANTOIN

It is bacteriostatic and but bactericidal

against many gram positive and negative

organisms in higher concentration and

acidic urine. Pseudomonas aeruginosa and

various strains of Proteus are resistant. It

antagonizes the action of nalidixic acid and

its activity is enhanced by lower pH. After

oral administration it is rapidly and

completely absorbed from GIT,

metabolized in liver and less than half is

excreted unchanged in urine.

It is used exclusively for urinary tract

infections. The side effects include nausea,

vomiting, diarrhoea, anorexia, leukopenia,

haemolytic anaemia, jaundice, dizziness and

headache. On chronic use can lead to periph-

eral neuritis and interstitial pulmonary fi-

brosis.

METHENAMINE

Methenamine mandelate is a salt of

mandelic acid and methenamine and both of

these possess property of urinary antiseptic.

It is rapidly absorbed in gastrointestinal tract

and excreted unchanged in urine, where it

broken down in acidic pH (< 5) of urine and

formaldehyde is released, which inhibits most

of the bacteria. It is administered with sodium

biphosphate, mandelic acid or ascorbic acid

to keep the urinary pH below 6. Its use is

restricted to chronic, resistant type of UTI.

Adverse effects are gastritis, hematuria,

chemical cystitis and skin rash. It is

contraindicated in renal failure and hepatic

insufficiency.

Table 9.2.2: Classification of urinary antiseptics.

Nitrofurantoin (FURADANTIN) 50-100 mg QID

Methenamine (as mendelate & hippurate) 1 g TDS-QID

Phenazopyridine (PYRIDIUM) 200-400 mg TDS

Other antimicrobial agents used in urinary tract infection e.g. sulfonamides, quinolones, penicillins,

cephalosporins etc. (details are discussed in respective sections).