Me NaPhos MB Hyo 1

ME NAPHOS MB HYO 1- methenamine, sodium phosphate, monobasic, monohydrate, methylene blue anhydrous and hyoscyamine sulfate anhydrous tablet
Method Pharmaceuticals

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 contains:

Methenamine, USP …………………………… 81.6 mg
Monobasic Sodium Phosphate, USP ……… 40.8 mg
Methylene Blue ………………………………… 10.8 mg
Hyoscyamine Sulfate …………………………. 0.12 mg

Inactive Ingredients include:

Cellulose, Mannitol, Croscarmellose Sodium, Magnesium
Stearate, FD&C Blue #1

HYOSCYAMINE SULFATE is an alkaloid of belladonna.
Exists as a white crystalline powder. Affected by light It
is very soluble in water; freely soluble in alcohol;
practically insoluble in ether.
METHENAMINE exists as colorless, lustrous crystals or
white crystalline powder. Its solutions are alkaline to
litmus. Freely soluble in water; soluble in alcohol and in

METHYLENE BLUE exists as dark green crystals. It is
soluble in water and in chloroform; sparingly soluble in

crystalline powder. Its solutions are acidic to litmus. It is
freely soluble in water and practically insoluble in

This product is not an Orange Book (OB) rated
product, therefore all prescriptions using this
product shall be pursuant to state statutes as
applicable. There are no claims of bioequivalence
or therapeutic equivalence.


HYOSCYAMINE is a parasympatholytic which relaxes
smooth muscles and thus produces an antispasmodic
effect. It is well absorbed from the gastrointestinal tract
and is rapidly distributed throughout body tissues. Most
is excreted in the urine within 12 hours, 13% to 50%
being unchanged.

Its biotransformation is hepatic. Its protein binding is

METHENAMINE degrades in an acidic urine environment
releasing formaldehyde which provides bactericidal or
bacteriostatic action. It is well absorbed from the
gastrointestinal tract. 70% to 90% reaches the urine
unchanged at which point it is hydrolyzed if the urine is
acidic. Within 24 hours it is almost completely (90%)
excreted; of this amount at pH 5, approximately 20% is
formaldehyde. Protein binding: some formaldehyde is
bound to substances in the urine and surrounding
tissues. Methenamine is freely distributed to body tissue
and fluids but is not clinically significant as it does not
hydrolyze at pH greater than 6.8.

METHYLENE BLU E possesses weak antiseptic properties.
It is well absorbed in the gastrointestinal tract and is
rapidly reduced to leukomethylene blue which is
stabilized in some combination form in the urine. 75%
is excreted unchanged.

acid pH in the urine necessary for the degradation of


ME/NaPhos/MB/Hyo 1 Tablets is indicated for the
treatment of symptoms of irritative voiding. Indicated
for the relief of local symptoms, such as hypermotility
which accompany lower urinary tract infections and as
antispasmodic. Indicated for the relief of urinary tract
symptoms caused by diagnostic procedures.


Do not exceed recommended dosage. If rapid pulse,
dizziness, or blurring of vision occurs discontinue use


(Pregnancy Category C)
hyoscyamine and methenamine cross the placenta.
Studies have not been done in animals or humans. It is
not known whether ME/NaPhos/MB/Hyo 1
Tablets cause fetal harm when administered to a
pregnant woman or can affect reproduction capacity.
ME/NaPhos/MB/Hyo 1 Tablets should be given to
a pregnant woman only if clearly needed.


problems in humans have not been documented;
however, methenamine and traces of hyoscyamine are
excreted in breast milk.

Prolonged use

there have been no studies to establish the safety of
prolonged use in humans. No known long-term animal
studies have been performed to evaluate carcinogenic


infants and young children are especially susceptible to
the toxic effect of the belladonna alkaloids.


use with caution in elderly patients as they may respond
to usual doses of hyoscyamine with excitement,
agitation, drowsiness, or confusion.

Drug Interactions

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 because of secondary antimuscarinic
activities of these medications); antacids/antidiarrheals
(may reduce absorption of hyoscyamine, 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; antimyasthenics (concurrent use with
hyoscyamine 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).
Patients should be advised that the urine may become
blue to blue green and the feces may be discolored as a
result of the excretion of methylene blue.


Cardiovascula r – rapid pulse, flushing

Central Nervous System – blurred vision, dizziness

Respiratory – shortness of breath or troubled

Genitourinary – difficulty micturition, acute urinary

Gastrointestinal – dry mouth, nausea/vomiting

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