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Generic name: hyoscyamine sulfate, methenamine, phenyl salicylate, sodium phosphate, monobasic and methylene blue
Dosage form: tablet
Drug class: Urinary antispasmodics

Medically reviewed by Last updated on Nov 23, 2020.

Disclaimer: This drug has not been found by FDA to be safe and effective, and this labeling has not been approved by FDA. For further information about unapproved drugs, click here.

Each tablet for oral administration contains:
Hyoscyamine Sulfate 0.12 mg
81.6 mg
Phenyl Salicylate 36.2 mg
Sodium Phosphate Monobasic 40.8 mg
Methylene Blue 10.8 mg

Inactive Ingredients: Cetyl Alcohol, Crospovidone, Dicalcium Phosphate, Ethylcellulose, F&DC Blue #1 Aluminum Lake, Hydroxypropyl Methylcellulose, Magnesium Stearate, Microcrystalline Cellulose, Polyethylene Glycol, Polyvinyl Alcohol, Sodium Lauryl Sulfate, Stearic Acid, Talc, Titanium Dioxide.

Hyoscyamine Sulfate. [620-61-1] [3(S)-endo]-α-(Hydroxymethyl)-benzeneacetic acid 8-methyl-8-azabicyclo[3.2.1]oct-3-yl ester sulfate(2:1)(salt); 1αH,5αH-tropan-3α-ol(-)-tropate (ester) sulfate(2:1)(salt); 3α-tropanyl S-(-)-tropate; I-tropic acid ester with tropine; I-tropine tropate. C34H48N2O10S. Hyoscyamine Sulfate is an alkaloid of belladonna. Exists as a white crystalline powder. Its solutions are alkaline to litmus. Affected by light, it is slightly soluble in water; freely soluble in alcohol; sparingly soluble in ether.

Methenamine. [100-97-0] 1,3,5,7-Tetraazatricyclo [3.3.1.-1 3,7] decane; hexamethylenetetramine; HMT; HMTA; hexamine; 1,3,5,7-tetraazaadamantane hexamethylenemine; Uritone; Urotropin. C6H12N4; mol wt 140.19; C 51.40%, H 8.63%, N 39.96%. Methenamine (hexamethylenetetramine) exists as colorless, lustrous crystals or white crystalline powder. Its solutions are alkaline to litmus. Freely soluble in water, soluble in alcohol and in chloroform.

Phenyl Salicylate. [118-55-8] 2-Hydroxybenzoic acid phenyl ester; Salol. C13H10O3; mol wt 214.22, C 72.89%, H 4.71%, O 22.41%. Made by the action of phosphorus oxy-chloride on a mixture of phenol and salicylic acid. Phenyl Salicylate exists as white crystals with a melting point of 41°-43°C. It is very slightly soluble in water and freely soluble in alcohol.

Sodium Phosphate, Monobasic. [7558-80-7] Phosphoric acid sodium salt (1:1); Sodium biphosphate; sodium dihydrogen phosphate; acid sodium phosphate; monosodium orthophosphate; primary sodium phosphate; H2NaO4P; mol wt 119.98, H 1.68%, Na 19.16%, O 53.34%, P 25.82%. Monohydrate, white, odorless slightly deliquesce crystals or granules. At 100°C loses all its water; when ignited it converts to metaphosphate. It is freely soluble in water and practically insoluble in alcohol. The aqueous solution is acid. pH of 0.1 molar aqueous solution at 25°C: 4.5.

Methylene Blue. [61-73-4] 3,7-Bis(dimethylamino) phenothiazin-5-ium chloride; C.I. Basic Blue 9; methylthioninium chloride; tetramethylthionine chloride; 3,7-bis(dimethylamino) phenazathionium chloride. C16H18ClN3S; mol wt 319.85, C 60.08%, H 5.67%, Cl 11.08%, N 13.14%, S 10.03%. Methylene Blue (Methylthionine chloride) exists as dark green crystals. It is soluble in water and in chloroform; sparingly soluble in alcohol.

Indications and Usage for Darcalma

Darcalma is indicated for the treatment of symptoms of irritative voiding. Indicated for the relief of local symptoms, such as inflammation, hypermotility, and pain, which accompany lower urinary tract infections. Indicated for the relief of urinary tract symptoms caused by diagnostic procedures.

Darcalma Dosage and Administration


Adults: One tablet 4 times per day by mouth, followed by liberal fluid intake.
Older Children: Dosage must be individualized by physician.
Not recommended for use in children younger than six years.


Darcalma is contraindicated in patients hypersensitive to any of its ingredients. Risk benefits should be carefully considered when the following medical problems exist: achalasia of esophagus, atony of colon, diseases of cardiovascular system, gastrointestinal hemorrhage; glaucoma; hemolytic anemia from pyruvate kinase and G6PD deficiencies, infected urolithiasis, myasthenia gravis, paralytic ileus, severe ulcerative colitis, toxic megacolon; acute urinary retention may be precipitated in obstructive uropathy (such as bladder neck obstruction due to prostatic hypertrophy).

Warnings and Precautions

Do not exceed recommended dosage. This drug may make you dizzy or drowsy or cause blurred vision; use caution while driving, using machinery, or doing any activity that requires alertness or clear vision. Limit alcohol consumption. Cross sensitivity and/or related problems – patients intolerant of belladonna alkaloids or salicylates may be intolerant of this medication also. Delay in gastric emptying could complicate the management of gastric ulcers. There have been no studies to establish the safety of prolonged use of this product in humans. No known long-term animal studies have been performed to evaluate carcinogenic potential.

Adverse Reactions

Cardiovascular: rapid heartbeat, flushing
Central Nervous System: blurred vision, dizziness, drowsiness
Genitourinary: difficulty micturition, acute urinary retention
Gastrointestinal: dry mouth, nausea and vomiting
Respiratory: shortness of breath or trouble breathing

Serious allergic reactions to this drug are rare. Seek immediate medical attention if you notice symptoms of a serious allergic reaction, including itching, rash, severe dizziness, swelling or trouble breathing.

This medication can cause urine and sometimes stools to turn blue-green. This effect is harmless and will subside after medication is stopped.

Call your doctor or physician for medical advice about side effects. The following number does not provide medical advice, but in the U.S. you may report suspected side effects to the FDA at 1-800-FDA-1088.

Drug Interactions

This drug should not be used with the following medications because very serious interactions may occur: live influenza virus vaccine, pramlintide. Because of this product's effect on gastrointestinal motility and gastric emptying, it may decrease the absorption of other oral medications during concurrent use such as: urinary alkalizers; thiazide diuretics (may cause the urine to become alkaline reducing the effectiveness of Methenamine by inhibiting its conversion to formaldehyde); antimuscarinics (concurrent use may intensify antimuscarinic effects of Hyoscyamine Sulfate because of secondary antimuscarinic activities of these medications); antacids/antidiarrheals (may reduce absorption of Hyoscyamine Sulfate, concurrent use with antacids may cause urine to become alkaline, reducing effectiveness of Methenamine by inhibiting its conversion to formaldehyde). Doses of these medications should be spaced 1 hour apart from doses of Hyoscyamine Sulfate; antimyasthenics (concurrent use with Hyoscyamine Sulfate may further reduce intestinal motility); ketoconazole (patients should be advised to take this combination at least 2 hours after ketoconazole); monoamine oxidase (MAO) inhibitors (concurrent use may intensify antimuscarinic side effects), opioid (narcotic analgesics may result in increased risk of severe constipation); sulfonamides (these drugs may precipitate with formaldehyde in the urine, increasing the danger of crystalluria). This is not a complete list of all drug interactions. Tell your doctor or pharmacist of all prescription medications prior to use.

Drug Abuse and Dependence

A dependence on the use of Darcalma has not been reported nor expected based on the pharmacology of the ingredients contained in Darcalma.


By exceeding the recommended dosage of Darcalma, symptomology related to the overdose of its individual active ingredients may be expected as follows:

Hyoscyamine Sulfate: Symptoms associated with overdosage of Darcalma will most probably be manifested in the symptoms related to overdosage of alkaloid Hyoscyamine Sulfate. Such symptoms as dryness of mucous membranes; dilation of pupils, hot, dry, flushed skin; hyperpyrexia; tachycardia; palpitations; elevated blood pressure; coma; circulatory collapse and death from respiratory failure can occur due to overdosage of these alkaloids.

Methenamine: If large amounts of the drug (2-8 g daily) are used over extended periods (3-4 weeks), bladder and gastrointestinal irritation, painful and frequent micturition, albuminuria and gross hematuria may be expected.

Phenyl Salicylate: Symptoms of Phenyl Salicylate overdosage include burning pain in throat and mouth, white necrotic lesions in the mouth, abdominal pain, vomiting, bloody diarrhea, pallor, sweating, weakness, headache, dizziness and tinnitus. The symptoms, however, are not expected to be discernible from those associated with the other active ingredients in Darcalma.

Sodium Phosphate Monobasic: Symptoms of Sodium Biphosphate overdosage may include diarrhea, dehydration, and electrolyte imbalances.

Methylene Blue: Symptoms of Methylene Blue overdosage associated with the overdosage of Darcalma are not expected to be discernible from those associated with other active ingredients in Darcalma.

Treatment: Emesis or gastric lavage. Slow intravenous administration of physostigmine in doses of 1 to 4 mg (0.5 to 1 mg in children), repeated as needed in one to two hours to reverse severe antimuscarinic symptoms.

Administration of small doses of diazepam or baclofen to control excitement and seizures. Artificial respiration with oxygen if needed for respiratory depression. Adequate re-hydration is required. Symptomatic treatment as determined by a doctor.

If overdose is suspected, contact your local poison center or emergency room immediately. US residents can contact the US National Poison Hotline at 1-800-222-1222.

How is Darcalma Supplied

Darcalma is available as a blue tablet, imprinted "RE 287": bottles of 100 tablets, NDC 68032-287-10. Dispense in a tight, light-resistant container as defined in the USP/NF with a child resistant closure.

Store at controlled room temperature 15°-30°C (59°- 86°F). Keep in a cool, dry place.

Keep this and all drugs out of reach of children.


Rx Only


hyoscyamine sulfate, methenamine, phenyl salicylate, sodium phosphate, monobasic, methylene blue tablet
Product Information
Product Type HUMAN PRESCRIPTION DRUG LABEL Item Code (Source) NDC:68032-287
Route of Administration ORAL DEA Schedule
Active Ingredient/Active Moiety
Ingredient Name Basis of Strength Strength
Hyoscyamine Sulfate (Hyoscyamine) Hyoscyamine Sulfate 0.12 mg
Methenamine (Methenamine) Methenamine 81.6 mg
Phenyl Salicylate (Phenyl Salicylate) Phenyl Salicylate 36.2 mg
Sodium Phosphate, Monobasic (Sodium Cation) Sodium Phosphate, Monobasic 40.8 mg
Methylene Blue (Methylene Blue) Methylene Blue 10.8 mg
Inactive Ingredients
Ingredient Name Strength
Cetyl Alcohol
Product Characteristics
Color blue Score no score
Shape OVAL Size 10mm
Flavor Imprint Code RE;287
# Item Code Package Description
1 NDC:68032-287-10 100 TABLET (TABLET) in 1 BOTTLE
Marketing Information
Marketing Category Application Number or Monograph Citation Marketing Start Date Marketing End Date
unapproved drug other 12/22/2008 07/31/2011
Labeler - River's Edge Pharmaceuticals, LLC (133879135)
River's Edge Pharmaceuticals, LLC

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