methenamine/hyoscyamine (Discontinued)

Brand and Other Names:Prosed DS, Darpaz, more...Urogesic Blue
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

methenamine/hyoscyamine

tablet

  • 81mg/0.12mg

tablet, capsule

  • 120mg/0.12mg

Urinary Tract Irritative Voiding Symptoms

1 tablet/capsule PO q6hr with liberal fluid intake

Use only after eradication of UTI by other appropriate antibiotic

Methenamine: Indicated for prophylaxis/suppression for chronic recurring UTIs when long-term therapy is required

Hyoscyamine: Adjunctive treatment for lower urinary tract hypermotility and spasm

Dosage Forms & Strengths

tablet

  • 81 mg/0.12mg

tablet, capsule

  • 120 mg/0.12mg

Urinary Tract Infection Prophylaxis

<16 years: Safety/efficacy not established

≥16 years: 1 tablet/capsule PO q6hr with liberal fluid intake

Use only after eradication of UTI by other appropriate antibiotic

Methenamine: Indicated for prophylaxis/suppression for chronic recurring UTIs when long-term therapy is required

Hyoscyamine: Adjunctive treatment for lower urinary tract hypermotility and spasm

Avoid hyoscyamine except in short-term situations to decrease secretions; high incidence of anticholinergic effects (Beers criteria)

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Interactions

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                    Adverse Effects

                    >10%

                    Hyoscyamine

                    • Dry skin

                    1-10%

                    Methenamine

                    • Dysuria
                    • Discoloration of urine (blue)
                    • Gastric upset
                    • Nausea
                    • Rash

                    Hyoscyamine

                    • Blurred vision
                    • Constipation
                    • Dysphagia
                    • Photosensitivity

                    <1%

                    Hyoscyamine

                    • Headache
                    • Orthostatic hypotension
                    • Tachycardia
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                    Warnings

                    Contraindications

                    Methenamine

                    • Hypersensitivity to methenamine or tartrazine (FD&C Yellow No. 5)
                    • Renal or severe hepatic insufficiency
                    • Concurrent sulfonamides or acetazolamide may form insoluble precipitate in urine

                    Hyoscyamine

                    • Hypersensitivity to hyoscyamine or related compounds
                    • Closed-angle glaucoma, myasthenia gravis, hemorrhage w/ cardiovascular instability, paralytic ileus, intestinal atony of elderly/debilitated pt, obstructive uropathy, toxic megacolon, GI obstruction, tachycardia secondary to cardiac insufficiency or thyrotoxicosis
                    • Breastfeeding

                    Cautions

                    Methenamine

                    • Large doses may cause bladder irritation, urinary frequency, albuminuria, and hematuria
                    • Maintain acidic pH of urine, esp. when treating urea-splitting organisms (eg, Proteus, Pseudomonas)
                    • Monitor LFTs, especially with history of liver impairment
                    • Safe use not established during pregnancy, especially 1st and 2nd trimester
                    • May precipitate uric acid stones in patients with gout

                    Hyoscyamine

                    • Renal/hepatic impairment, BPH, CHF, CAD, HTN, COPD, hiatal hernia, reflux esophagitis, mitral stenosis, brain damage or spastic paralysis in children, salivary secretion disorder, Down syndrome, autonomic neuropathy, hyperthyroidism, tachyarrythmia, toxin-mediated diarrhea
                    • Elderly
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                    Pregnancy & Lactation

                    Pregnancy Category: C

                    Lactation: hyoscyamine and methenamine excreted in human milk; caution in breastfeeding women

                    Pregnancy Categories

                    A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

                    B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

                    C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

                    D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

                    X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

                    NA: Information not available.

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                    Pharmacology

                    Mechanism of Action

                    Methenamine: Hydrolyzed in acidic urine to ammonia and formaldehyde, which are bactericidal agents; does not convert to formaldehyde in serum

                    Hyoscyamine: Elicits anticholinergic activity; decreases urinary spasms with cystitis

                    Additional ingredients in some products: Methylene blue (weak antiseptic properties); sodium phosphate monobasic (acidifier); phenyl salicylate (mild analgesic)

                    Absorption

                    Well absorbed; 10-30% hydrolyzed by gastric acid unless enteric coated tablet

                    Peak Urine Time: (formaldehyde) 2 hr for hippurate salt, 3-8 hr for mandelate salt

                    Metabolism

                    Liver (10-25%)

                    Elimination

                    Half-Life: 3-6 hr

                    Excretion: urine (90%)

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                    Images

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                    Patient Handout

                    A Patient Handout is not currently available for this monograph.
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                    Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.