NALIDIXIC ACID 500MG
Active substance(s): NALIDIXIC ACID
NAME OF THE MEDICINAL PRODUCT
Nalidixic Acid 500 mg
QUALITATIVE AND QUANTITATIVE COMPOSITION
Nalidixic Acid BP 500.00 mg
For the treatment of acute or chronic infections, especially those of the urinary
tract caused by Gram-negative organisms, other than pseudomonas species,
sensitive to Nalidixic Acid. It may also be used for the treatment of
gastrointestinal gram- negative infections sensitive to Nalidixic Acid where
appropriate, though relapse rate and treatment failure in gastrointestinal
infection may be more common.
Posology and method of administration
For oral administration only. Nalidixic acid should be taken on an empty
stomach, preferably one hour before a meal.
Adults (including the elderly):
For acute infections 1 g four times daily for at least seven days, reducing to
0.5 g four times a day for chronic infections.
Children over 3 months:
Oral suspension is recommended.
The maximum recommended dose is 50 mg/kg bodyweight per day, in divided
doses. Where prolonged treatment is necessary it may be possible to reduce
the dose to 30 mg/kg bodyweight without loss of therapeutic benefit.
Patients with renal-failure:
The normal dose of nalidixic acid may be employed in patients with creatinine
clearance of more than 20 ml/minute. Dosage should be halved in patients
with creatinine clearance of 20 ml/minute or less.
Nalidixic Acid is contraindicated for infants less than 3 months of age and
patients with a history of convulsive disorders, porphyria or hypersensitivity to
Nalidixic Acid or related compounds.
Special warnings and precautions for use
Particular caution is advised in patients with a known allergic disposition.
Nalidixic Acid is mainly metabolised by the liver and should therefore be used
with caution in patients with liver disease. Care should be exercised in treating
patients with renal failure; the normal dose of Nalidixic Acid may be
administered to patients with creatinine clearance of more than 20 ml/minute but
dosage should be halved in patients with creatinine clearance of 20 ml/minute or
Patients taking Nalidixic Acid should avoid excessive exposure to sunlight
Caution should be observed in patients with severe cerebral arteriosclerosis or
glucose-6-phosphate dehydrogenase deficiency.
When Nalidixic Acid is given to patients on anticoagulant therapy, it may be
necessary to reduce the anticoagulant dosage.
Nalidixic Acid has been shown to induce lesions in weight-bearing joints of
young animals. The relevance of this to man is unknown. The possible risk of
late degenerative joint changes in young patients receiving Nalidixic Acid
preparations should therefore be considered. If symptoms of arthralgia occur,
treatment with Nalidixic Acid should be stopped.
Not recommended for infants less than 3 months of age (see section 4.3).
Caution should be observed and therapy discontinued if patients develop signs
or symptoms suggestive of an increase in intracranial pressure, psychosis or
other toxic manifestations.
Blood count; renal and liver function should be monitored periodically if
treatment is continued for more than two weeks.
If the clinical response is unsatisfactory or if relapse occurs, therapy should be
reviewed in the light of appropriate culture and sensitivity tests. If bacterial
resistance to nalidixic acid develops it does so usually within 48 hours. Crossresistance between nalidixic acid and other quinolone derivatives such as
oxolinic acid and cinoxacin have been observed.
Interaction with other medicinal products and other forms of interaction
Nalidixic Acid may interact with anticoagulants due to competition for protein
binding sites and it may therefore be necessary to reduce the anticoagulant
dosage and monitor the prothrombin time during coadministration, until a
satisfactory prothrombin ratio is achieved.
There have been reports of serious gastrointestinal toxicity following
concomitant use of nalidixic acid and melphalan.
Nalidixic Acid in therapeutic doses can interfere with the estimation of urinary
17-ketosteroids and may cause high results in the assay of urinary
vanilmandelic-acid (Pisano method).
When testing for glycosuria in patients receiving Nalidixic Acid, glucosespecific methods based on glucose oxidase should be used because copper
reduction methods may give false-positive results.
Active proliferation of the organisms is a necessary condition for the
antibacterial activity of Nalidixic Acid: the action of Nalidixic Acid may
therefore be inhibited by the presence of other antibacterial substances,
especially bacteriostatic agents such as tetracycline, chloramphenicol and
nitrofurantoin which is antagonistic to Nalidixic Acid in vitro.
Nalidixic Acid also interacts with probenecid, which inhibits the tubular
secretion of Nalidixic Acid. This may reduce the efficacy of the product in the
treatment of urinary tract infections.
It is possible that there will be increased risk of nephrotoxicity with
Pregnancy and lactation
Although there is no evidence that Nalidixic Acid has any harmful effect
during pregnancy, careful consideration should be given to its use during the
first trimester. When treating women who are breast feeding, consideration
should be given to the fact that traces of Nalidixic Acid are excreted in the
Effects on ability to drive and use machines
No specific warning.
Reactions reported after oral administrations of Nalidixic Acid include CNS
side effects: Drowsiness, weakness, headache, dizziness and vertigo.
Reversible subjective visual disturbances without objective findings have
occurred infrequently (generally with each dose during the first few days of
treatment). These reactions include overbrightness of lights, change in colour
perception, difficulty in focusing, decrease in visual acuity, and double vision.
They usually disappeared promptly when dosage was reduced or therapy was
Toxic psychosis or brief convulsions have been reported rarely, usually
following excessive doses. In general, the convulsions have occurred in
patients with predisposing factors such as epilepsy or cerebral arteriosclerosis.
In infants and children receiving therapeutic doses of Nalidixic Acid,
increased intercranial pressure with bulging anterior fontanelle, papilloedema,
and headache have occasionally been observed. A few cases of 6th cranial
nerve palsy have been reported. Although the mechanisms of these reactions
are unknown, the signs and symptoms usually disappeared rapidly with no
sequelae when treatment was discontinued.
Gastrointestinal: Abdominal pain, nausea, vomiting and diarrhoea.
Allergic: Rash, pruritus, urticaria, angio-oedema, eosinophilia, arthralgia with
joint stiffness and swelling, and rarely, anaphylactoid reaction.
Photosensitivity reactions consisting of erythema and bullae on exposed skin
surfaces usually resolve completely in 2 weeks to 2 months after Nalidixic
Acid is discontinued; however, bullae may continue to appear with successive
exposures to sunlight or with mild skin trauma for up to 3 months after
discontinuation of the drug (see 4.4.).
Other: Rarely cholestasis, parathaesia, metabolic acidosis, thrombocytopenia,
leukopenia, or haemolytic anaemia, sometimes associated with glucose-6phosphate dehydrogenase deficiency.
In adults, symptoms of overdosage have been noted following single doses of
20 and 25 g. These have included toxic psychosis and convulsions. Occasional
reports of metabolic acidoses have occurred in association with overdosage,
use in infants under the age of 3 months, or overdose with concurrent use of
In an emergency, it is suggested that the stomach should be emptied, and
symptomatic treatment applied as necessary, a particular watch being kept for
central or respiratory depression.
Nalidixic acid is bactericidal and inhibits gram-negative micro-organisms,
escherichia coli, klebsiella aerogenes, kleb. pneumoniae, salmonella
spp., shigella spp., and proteus spp. Brucella spp. may be sensitive. Minimum
concentrations are reported to range from about 5 to 75 µg per ml.
are inhibited by 10 µg per ml or less. Pseudomonas aeruginosa
is usually resistant. Bacterial resistance may develop rapidly, sometimes within a
few days and cross- resistance with oxolinic acid occurs.
Antibacterial activity of nalidixic acid is not significantly affected by
differences in urinary pH.
Nalidixic acid is readily absorbed from the gastrointestinal tract. The plasma
half-life is about 90 minutes and peak plasma concentrations of 20 to 50 μg
per ml have been reported 2 hours after the administration of 1 g by mouth.
About 90% of the drug is bound to plasma proteins.
It is rapidly metabolised, mainly to hydroxy-nalidixic acid which also has
antibacterial activity and accounts for about 30% of active drug in the blood.
About 80% of a dose appears in the urine within 8 hours, most of the nalidixic
acid and its active metabolite having been conjugated in the liver to inactive
glucuronides but urinary concentrations of free drug and active metabolite
ranging from 25 to 250 μg per ml are achieved after a single 1 g dose.
Hydroxynalidixic acid accounts for about 85% of this activity.
Only traces of nalidixic acid appear in milk and cerebrospinal fluid. About 4%
of a dose is excreted in the faeces.
Preclinical safety data
List of excipients
Sodium starch glycollate
Iron oxide E172
48 months all pack sizes.
Special precautions for storage
Store below 25°C in a dry place. Keep container well closed.
Nature and contents of container
High density polystyrene containers with polythene lids and/or polypropylene
containers with polypropylene or polythene lids and polyurethane or polythene
Pack sizes: 56, 100, 112, 500, 1000
Special precautions for disposal
No special instructions.
MARKETING AUTHORISATION HOLDER
Chelonia Healthcare Limited
Boumpoulinas 11, 3rd Floor
MARKETING AUTHORISATION NUMBER(S)
DATE OF FIRST AUTHORISATION/RENEWAL OF THE
DATE OF REVISION OF THE TEXT
Source: Medicines and Healthcare Products Regulatory Agency
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