Name of the Urinary Antiseptic Drugs
- Nitrofurantoin
- Methenamine
- Nalidixic acid
- Phenazopyridine
1.Nitrofurantoin
| Nitrofurantoin |
| Availability Capsules: 25 mg, 50 mg, 100 mg (macrocrystals) Capsules (extended release): 100 mg (macrocrystals) Oral suspension: 25 mg/5 ml Tablets: 50 mg, 100 mg (macrocrystals) |
| Indications and dosages ➣ Active urinary tract infections (UTIs) Adults: 50 to 100 mg P.O. q.i.d. or 100 mg q 12 hours (extended-release), continued for 1 week, or for 3 days after urine becomes sterile Children older than 1 month: 5 to 7 mg/kg/day P.O. in four divided doses, continued for 1 week, or for 3 days after urine becomes sterile ➣ Chronic suppression of UTIs Adults: 50 to 100 mg P.O. at bedtime Children: 1 mg/kg/day P.O. in one or two divided doses |
Mechanism of Action
Inactivates or alters bacterial ribosomal proteins and other macromolecules. This action of nitrofurantoin inhibits bacterial protein synthesis, aerobic energy metabolism, DNA synthesis, RNA synthesis, and cell wall synthesis. Nitrofurantoin is bacteriostatic at low doses and bactericidal at higher doses.
Administration
- As appropriate, obtain specimens for repeat urine culture and sensitivity tests before therapy.
- To avoid GI upset and increase drug bioavailability, give with food or milk.
Pharmacokinetics
Absorption:
- Well, absorbed; macrocrystalline form absorbed more slowly due to slower dissolution (causes less GI distress)
- Blood concentrations at therapeutic dosage are usually low
- Bioavailability: Increased with food
Distribution
- Highly soluble in urine; lacks broader tissue distribution
- Crosses placenta, but not well distributed
- Protein bound: Approximately 60-90%
Metabolism:
- Reduced by bacterial flavoproteins to reactive intermediates
- Body tissues (except plasma) metabolize 60% of drug to inactive metabolites
Elimination
- Half-life: 20-60 min; prolonged with renal impairment
- Excretion: Urine (40%); feces (small amounts)
Contraindications
- Hypersensitivity to drug or parabens (oral suspension)
- Oliguria, anuria, or significant renal impairment
- Pregnancy near term (38 to 42 weeks’ gestation), imminent labor onset, labor and delivery
- Infants younger than 1 month
Precautions:
- Diabetes mellitus, renal impairment
- Blacks and patients of Mediterranean or near-Eastern descent (because of possible G6PD deficiency)
- Elderly or debilitated patients
- Pregnant (to week 32) or breastfeeding patients.
Adverse reactions
- CNS: dizziness, drowsiness, headache, asthenia, peripheral neuropathy, vertigo
- CV: chest pain EENT: nystagmus
- GI: nausea, vomiting, diarrhea, abdominal pain, anorexia, parotitis, pancreatitis
- Hematologic: eosinophilia, agranulocytosis, thrombocytopenia, leukopenia, granulocytopenia, G6PD deficiency anemia, hemolytic anemia, megaloblastic anemia
- Hepatic: hepatitis, hepatic necrosis
- Musculoskeletal: arthralgia, myalgia Respiratory: asthma attacks, pulmonary hypersensitivity reactions including diffuse interstitial pneumonitis (with prolonged therapy)
- Skin: rash, exfoliative dermatitis, alopecia, pruritus, urticaria, angioedema, photosensitivity, Stevens-Johnson syndrome Other: drug fever, chills, superinfection (limited to urinary tract), hypersensitivity reactions including anaphylaxis, lupus-like syndrome
Patient monitoring
- Monitor patient’s response to therapy. Assess urine culture and sensitivity tests.
- Watch for and immediately report peripheral neuropathy.
- Assess respiratory status. Watch for signs and symptoms of serious pulmonary hypersensitivity reaction.
- Monitor CBC and liver function tests closely. Stay alert for evidence of hematologic and hepatic disorders.
- Evaluate patient for rash.
Patient teaching
- Instruct patient to take with food or milk at regular intervals around the clock.
- Advise patient to complete entire course of therapy.
- Tell patient not to take magnesiumcontaining drugs (such as antacids) during therapy.
- Caution patient not to drive or perform other hazardous activities until he knows how drug affects vision, concentration, and alertness.
- Tell patient to immediately report fever, chills, cough, chest pain, difficulty breathing, rash, bleeding or easy bruising, dark urine, yellowing of skin or eyes, numbness or tingling of fingers or toes, or intolerable GI distress.
- Advise female patient to avoid taking drug during pregnancy, especially near term.
- As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.
Nursing Considerations
- Obtain a specimen of patient’s urine for culture and sensitivity tests, as ordered; review test results if possible before giving nitrofurantoin.
- Give drug with food or milk to avoid staining teeth.
- Don’t crush or break capsules.
- Shake oral nitrofurantoin suspension before pouring dose, and mix with food or milk, as needed.
- Monitor patient for evidence of superinfection, such as abdominal pain, diarrhea, and fever. If patient develops diarrhea, it may indicate pseudomembranous colitis caused by Clostridium difficile. Notify prescriber and expect to withhold nitrofurantoin and treat with fluids, electrolytes, protein, and an antibiotic effective against C. difficile.
- Monitor patient for pulmonary and hepatic abnormalities because rare but severe reactions have occurred with nitrofurantoin use, especially in the elderly.
- Observe patient for changes in nervous function because peripheral neuropathy, although uncommon, may become severe or irreversible. Patients with renal impairment, anemia, diabetes mellitus, electrolyte imbalance, vitamin B deficiency, or debilitating disease are at higher risk for peripheral neuropathy
2.Methenamine
| Methenamine |
| Availability tablet, hippurate 1g tablet, mandelate 500mg ,1g |
| Indications and Dosages To prevent or suppress frequently recurring UTI caused by a wide variety of gram-negative and gram-positive bacteria (including enterococci, Escherichia coli, Micrococcus pyogenes, and staphylococci) in intermittently catheterized patients with neurogenic bladder Adults and adolescents. 1 g q.i.d. before meals and at bedtime. Children ages 6 to 12. 500 mg q.i.d., or 50 mg/kg daily in divided doses. Children under age 6. 18.4 mg/kg q.i.d. TABLETS (METHENAMINE HIPPURATE) Adults and adolescents. 1 g b.i.d. Children ages 6 to 12. 0.5 to 1 g every 12 hr |
Mechanism of Action
Hydrolyzes to formaldehyde and ammonia in an acidic environment, such as urine, producing greater amounts of formaldehyde as pH decreases. Formaldehyde has bactericidal action, possibly by denaturing proteins. To facilitate hydrolysis, methenamine is formulated with weak organic acid, such as hippuric acid or mandelic acid.
Pharmacokinetics
- Half-life: 4.3 hr
- Onset: 30 min
- Peak plasma time: 3-8 hr
- Vd: 0.56 L/kg
- Excretion: urine; methenamine 90% excreted w/in 24 hr; mandelic or hippuric acid may accumulate with severe renal impairment
Contraindications
Concurrent therapy with sulfonamides, hypersensitivity to methenamine, renal insufficiency, severe dehydration, severe hepatic disease
Adverse Reactions
- CNS: Headache
- CV: Edema
- EENT: Stomatitis
- GI: Abdominal cramps, anorexia, diarrhea, nausea, vomiting
- GU: Bladder irritation, crystalluria, dysuria,hematuria, proteinuria, urinary frequency
- RESP: Pulmonary hypersensitivity (dyspnea, pneumonitis)
- SKIN: Pruritus, rash, urticaria
Nursing Considerations
- Be aware that methenamine is used for prophylaxis; it isn’t recommended as primary treatment for UTI.
- Drug shouldn’t be given to patients with creatinine clearance less than 50 ml/min/ 1.73 m2.
- Before giving first dose, expect to obtain urine specimen for culture and sensitivity tests and to review test results if available.
- Plan to give methenamine mandelate around the clock to maintain a therapeutic blood level.
- Make sure patient receives adequate fluids.
- Expect to repeat culture and sensitivity tests if patient fails to improve.
Patient Teaching
- Instruct patient to take methenamine with food to avoid GI distress.
- Direct patient to drink extra fluids; avoid alkaline foods, such as milk, milk products, and most fruits; and avoid antacids that contain sodium bicarbonate or carbonate during methenamine therapy.
- Instruct patient to report painful urination, rash, or severe GI distress.
- Urge patient to comply with urine testing before and during long-term therapy
3.Nalidixic acid
| Nalidixic acid |
| Availability 250 mg/5 mL; 250 mg; 500 mg; 1 g |
| Indications and Dosages Nalidixic acid is indicated in the treatment of urinary tract infection caused by susceptible Gram-negative organisms, including Proteus species, Klebsiella species, Enterobacter species and Escherichia coli. Adult: initially is 1 g every 6 hours for 7 days reducing to 500 mg every 6 hours. Children: Infants and children 3 month of age and over Initial: Oral 13.75 mg per kg body weight every six hours for one or two weeks. Maintenance: Oral 8.25 mg per kg body weight every six hours or as prescribed by the physician. |
Mechanism of Action
Evidence exists for Nalidixic acid that its active metabolite, hydroxy nalidixic acid, binds strongly, but reversibly, to DNA, interfering with synthesis of RNA and, consequently, with protein synthesis
Contraindications
- Known hypersensitivity to the active component or to related compounds
- Infants younger than 3 months
- Porphyria
- History of convulsive disorders
- Coadministration with melphalan or other related cancer chemotherapeutic alkylating agents
Side Effects
Gastro-intestinal disturbances including nausea, vomiting, diarrhoea, haemolysis in G6PD deficiency, allergic reaction including urticaria, rashes, fever, arthralgia, eosinophilia, also myalgia, muscle weakness, phototoxicity, jaundice, visual disturbances and convulsions.
Precautions & Warnings
Risk-benefit must be considered during the first trimester of pregnancy and during breast feeding, impaired renal or hepatic function.
Administration advice:
- Perform disc susceptibility testing with the 30-mcg disc before using this drug, and during therapy if warranted by clinical response.
- May administer with or without meals
- Do not administer antacids (containing calcium, aluminum, magnesium), sucralfate, divalent or trivalent cations (e.g., iron), multivitamins containing zinc, or didanosine (chewable/buffered tablets) within 2 hours before or 2 hours after this drug.
Patient advice:
- Avoid missing doses and complete the entire course of therapy.
- Drink plenty of fluids.
- Stop this drug if tendon pain, inflammation, or rupture occurs; rest and do not exercise until diagnosis of tendinitis or tendon rupture excluded.
- Stop this drug and contact physician if symptoms of peripheral neuropathy (including pain, burning, tingling, numbness, weakness) develop.
- Consult physician at once if watery and bloody stools (with or without stomach cramps and fever) develop.
- Do not drive, operate machinery, or engage in other tasks that require mental alertness or coordination until you know how the drug affects you.
- Avoid excessive sunlight or artificial ultraviolet light during therapy; stop this drug if phototoxicity occurs.
Pharmacokinetics
- Bioavailability: 96%.
- Protein bound: 93%
- Metabolized in Hepatic
- Half-life: 1.1 to 2.5 hours
- Excretion: kidneys.
4.Phenazopyridine
| Phenazopyridine |
| Availability Tablets: 95 mg, 97.2 mg, 100 mg, 200 mg |
| Indications and dosages ➣ Pain caused by lower urinary tract irritation Adults: 200 mg P.O. t.i.d. Children: 12 mg/kg P.O. daily in three divided doses |
Mechanism of Action
Azo dye; acts directly on urinary tract mucosa when excreted, to produce local analgesic effect
Pharmacokinetics
Urine: Eliminated mainly through rapid excretion by kidneys (65% unchanged)
Metabolized by liver
Feces: Minor amount
Administration
- Give with or after meals.
- Discontinue after 2 days, as prescribed, when administering with antibiotics.
Contraindications
- Hypersensitivity to drug
- Renal insufficiency
Precautions :
- hepatitis
- pregnant or breastfeeding patients
- children younger than age 12.
Adverse reactions
- CNS: headache
- EENT: contact lens staining
- GI: GI disturbances
- GU: bright orange urine, renal toxicity
- Hepatic: hepatotoxicity
- Hematologic: haemolytic anemia, methemoglobinemia
- Skin: rash, pruritus
- Other: anaphylactoid-like reaction
Patient monitoring
- Monitor patient for symptomatic improvement of urinary tract infection (UTI).
- Assess follow-up urine culture after antibiotic therapy ends. Monitor for yellowing of skin or sclera. This change may indicate drug accumulation caused by impaired renal excretion, warranting drug withdrawal
Patient teaching
- Explain drug therapy and measures to help prevent UTI recurrence.
- Tell patient drug may discolor urine and tears and may stain clothing and contact lenses.
- Advise patient to contact prescriber promptly if symptoms don’t improve or if skin or eyes become yellow.
- As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the tests mentioned above
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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