Interacting drugs- summary

+ Nalidixic acid-

Warfarin-                                                                                                                         increase the effect of Warfarin

Anticoagulants-                                                                                                                    Enhances effect of warfarin and anisidione. The risk of bleeding may be incresed.The mechanism of action is unknown or complicated

Nirtrofurantoin-                                                                                                           Antogonise nitrofurantoin.

Melphelin-                                                                                                                        Serious G.I.T. toxicity with melphelan.

Food-                                                                                                                                   Food delays absorption,

Probenecid-                                                                                                             Probenecid prolongs half-life.

Chlorpheneramine-                                                                                        Chlorphemnazine and perphenazine potentiates antibacterial effect. Perphenazine 

Drug/Lab test interactions:

Urinary metabolites of nalidixic acid liberate glucoronic acid and produce false-positive urinary glucose results when Benedicts or Fehlings solution or Clinitest reagent tablets are used. Avoid this problem by using Clinistix or Test-Tape. Urinary 17-keto and ketogenic steroids may be falsely elevated due to an interaction betwen nalidixic acid and the m-dinitrobenzene used in the assay. In sich cases use the Porter-Sliber method.

Urinary tract infection. 

G.I.disturbances, bleeding, drowsiness, weakness, dizziness, visual disturbances, seizure, toxic psychosis, increased intracranial pressure, nausea, diarrhoea, rash, parathesias, metabolic acidosis, utricaria.photosensitivity. Rarely convulsions,blood dyscrasias,jaundice.

Hypersens,history of convulsive disorders,infants below 3 months.

Special precautions:

Severe liver & renal dysfunction, liver disease, respiratory depression, epilepsy. Avoid undue exposure to sunlight. Pregnancy and lactation.

Indications:

Urinary tract infection.

Dosage:

Adults- Initial 1g 4 times a day. Total dose 4g/day for 1 or 2 weeks. May be reduced to 2g/day.

Children-

Do not administer to infants below 3 months. Children more than 12 years of age - total daily dose 25mg/lb/day(55mg/kg/day) in 4 equally divided doses. May be reduced to 33mg/kg/day. Overdosage- Symptoms Toxic psychosis, convulsions, increased intracranial pressure, metabolic acidosis, vomiting, nausea, lethargy, may occur in patients taking more than the recommended dosage

Treatment

1. Reactions are short lived ( 2 to 3 hours) because the drug is rapidly excreted

2. If overdosage is noted early, gastric lavage is indicated.

3. If absorption has occured increase fluid administration and and have supportive measures available.

4. Anticonvulsants may be indicated in severe cases. 

Missed dose-

1. If you miss a dose of this medicine, take it as soon as possible.

2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

Classification: Antidiarrhoeal Patent position:

Major brands:

BACTOMET WIN-MEDICARE ENTROZYME-M-SUSP STADMED GRAMONEG RANBAXY NEGADIX CFL PHARMA Ceiling price Price /Rs. Notification Nalidixic acid 2744/kg S.O.318E Apr 26,'96 Domestic production 93/94 38.5T Demand projection 94/95 62T

Raw materials:

1.2 Amino methyl pyridine

2.Erthyl iodide or Triethyl phosphate or Dimethyl sulphate or Ethyl tosylate

3. Hysroxymethylene diethyl malonate

4. Ethyl acetoacetate

5.Triethyl orthoformate

6.Ethyl ethoxymethylene

7.Acetoacetate

8.Formaldehyde

9.Diethylamine

10.Amino picoline **

11.Ethoxymethylene malonic ester or Diethylethoxy methylene malonate ** concessional duty

1. May cause GI upset; take with food.

2. May produce drowsiness,dizziness, or blurred vision; observe caution while driving or performing other tasks requiring alertness,coordination or physical dexterity.

3. Avoid prolonged exposure to sunlight; photosensitivity may occur.

4. If seizure,psychotic behaviour(eg. hallucinations, incoherent speech, confusion) or severe headaches occur,while on nalidixic acid, contact the physician immediately

5.Allergies- tell your doctor if you have ever had any unusual or allergic reaction to nalidixic acid or related medicines. Also tell your doctor if you are allergic to any other substances, such as foods, presrvatives or dyes.

6.Pregnancy - not recommended for use in pregnancy.

7.Breast feeding- nalidixic acid passes into breast milk and may cause blod problems in nursing babies with glucose-6PD deficiency.

8. Children - not recommeded for use in infants up to 3 months of age since nalidixic acid has been shown to cause bone problems in young children.

9. Elderly- elderly patients has not been shown to cause different side effects or problems in older people than it does in younger adults.

10. Other medicines - Anticoagulants- patients taking nalidixic acid with anticoagulants may have an increased chance of bleeding

11. Other medical problems - Tell your doctor if you have any other medical problems especially - Convulsive disorders- or Hardening of the arteries in the brain- patients with these medical problems may have an increas chance of side effects affecting the nervous system. Glucose G6PD- patients with G6PD deficiency may have an increased chance of side effects affecting the blood. Kidney disease- or Liver disease- patients with liver disease may have an increase in side effects.

12. Missed dose - If you miss a dose of this medicine, take it as soon as possible. however, if it is almost time for the next dose, skip the missed dose. Do not double doses.

13. Storage - Keep out of reach of children. Store away from heat or direct sunlight. Do not store the capsule in bathroom, near the kitchen sink, or in other damp places.

14. Outdated medicines - Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of reach of children.

Pharmacology:

Nalidixic acid as a bacterial agent, appear to interfere with DNA polymerization.

Pharmacokinetics:

Nalidixic acid is well absorbed; peak serum levels of 20 to 40mcg/ml are attained 1 to 2 hours after an oral 1g dose. The drug concentrates in the renal tisue and seminal fluid; it does not penetrate prostatic tissue. Metabolism; Hepatic metabolism to hydroxynalidixic acid(activity similar to nalidixic acid) and inactive conjugates is followed by rapid excretion.

Food delays absorption,

Pregnancy:

Safe use during first trimester of pregnancy has not been established. The drug has been used during the the last two trimesters without apparent ill effects on mother or child.. No drug linked congenital defects have been reported.

Lactation:

Data are scant.

Children:

Nalidixic acid and related drugs can produce erotions of cartilage in weight bearing joints in animals. No lesions have been reported in humans. Use care in prepubertal children.