Interacting drugs- summary

+ Nitrofurantoin-

Antichlolinergics-                                                                                               anticholinergic drugs increase nitrofurantoin bioavailability by delaying gastric emptying and increasing absorption

Magnesium salts-                                                                                                     magnesium salts may delay or decrease the absorption of nitrofurantoin.

Norfloxacin-                                                                                                            antibacterial effect of norfloxacin in the urinary tract may be antagonised 

Nitrofurantoin +

Uricosurics-                                                                                                          administration of high doses of probenecid with nitrofurantoin decreases renal clearance and increases serum levels of nitrofurantoin. The result could be increased toxic effects.

Zalcitabine-                                                                                                                       these drugs are associated with peripheral neuropathy Avoid concomittant use when possible 

Drug/Lab test interactions- A false positive reaction for glucose in the urine may occur. This has been observed with Benedicts and Fehling solutions but not with glucose enzymatic test

. Drug/Food interactions- Bioavailability of nitrofurantoin is increased by food. Antagonises nalidixic acid. Absorption reduced by magnesium trisilicate. Probenecid reduces excretion thereby leading to increased toxicity. Urine excretion of pyridoxine increased. Antibacterial action potentiated by drugs which acidify the urine.

Indications:

Urinary tract infections

Dosage: Oral - Give with food and milk. Adults- 50 to 100mg 3 to 4 times a day with meals and bed time.

Children- 5 to 7mg/kg/24 hours given in single or divided dose. Overdosage- Symptoms Occassional incidents of acute overdosage of nitrofurantoin have not resulted in any specific symptoms other than vomiting

Treatment

1. Induction of emesis is recommended.

2. There is no specific antidote, buta high fluid intake should be maintained to promote urinary excretion of the drug.

3. It is dialyzable.

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.

Pulmonary Infiltrates-

Drugs causing adverse reactions- ( 386 )

1. Nitrofurantoin 2. Methysergide 3. Chlorambutil 4. Procarbazine 5. Busulfan 6. Melphalan 7. Cyclophosphamide 8. Azotropine 9. Bleomycin 10. Methorexata 11. Sulfonamides

1. Complete full couse of therapy; do not discontinue without notifying physician.

2. May cause GI upset, take with food and milk.

3. May cause brown discolouration of urine.

4. Notify physician, if fever, chills, cough, chest pain, difficult breathing, skin rash, numbness or tingling of fingers or toes, or intolerable GI upsets occurs

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

6.Pregnancy - nitrofurantoin should not be used if you are within a week or 2 of your delivery date or during labor and delivery.

7.Breast feeding- nitrofurantoin passes into breast milk in small amounts and may cause problems in nursing babies esoecially G6PD defiency

8. Children - no specific information comparing use of nitrates in children with use in other age groups

9.Elderly- elderly people are sensitive to the effects of nitrofurantoin. This may increase the chance of side effects during treatment.

10. Other medicines - Acetohydroxyamic acid or Antidiabetic oral or Methyldopa or Primaquine or Procainamide or Quinidine or Sulfonamides or Sulfoxone or Vitamin K - patients who take nitrofurantoin with any of these medicines may have an increase inside effects affecting the blood.

Carbammazepine or Chloroquine or Cisplatin or Cytarabine or Diphtheria or Disulfram or Ethotoin or Hydroxychloroquine or Lindane or Lithium or Mephenytoin or Mexilitine or Other anti-infectives by mouth or injerction or Pemoline or Phenytoin or Pyridoxime or Vincristine - patients who take nitrofurantoin with any of these medicines or who have received a DTP vaccine within 30 days or are going to receive DTP may have an increase in side effects affecting the nervous system

Probenecid or Sulfinpyrazone - patients who take nitrofurantoin with any of these medicines may have an increase inside effects

Quinine - patients who take nitrofurantoin with quinine may have an increase in side effects affecting the blood and the nervous system

11. Other medical problems - Tell your doctor if you have any other medical problems especially - Glucose 6 phosphate dehydranase ( G6PD defiency) - Kidney disease - the chance of side efects of this medicine may be increased and the medicine may be less effective in patients with kidney disease Lung disesase- or Nerve damage - patients with lung disease or nerve damage may have an increase in side efects when they take nitrofurantoin.

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. 13. 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:

Nitrofurantoin is a synthetic nitrofuran that is bacteriostatic in low concentrations(5 to 10mcg/ml) and bactericidal in higher concentrations. Nitrofurantoin may inhibit acetylcoenzyme.

Pharmacokinetics:

Well absobed from GI tract after oral administration. The macrocrystalline form is absorbed more slowly due to slower dissolution and causes less GI distress. Bioavailability of micro and macrocrystalline forms is enhanced by concomittant ingestion of food.

Bioavailabilty of nitrofurantoin is increased by food.

Pregnancy:

Safety for use in pregnancy has not been established

Lactation:

Nitrofurantoin is excreted in breast milk in very low concentrations. Safety for use in nursing mothers has not been established.

Children: Contraindicated in infants less than 1 month of age.