Monday, May 17, 2010

Acetaminophen, isometheptene, and dichloralphenazone

MEDICATION SAFETY ISSUES
Sound-alike/look-alike issues:
Midrin® may be confused with midodrine, Mydfrin®

Duplicate therapy issues: This product contains acetaminophen, which may be a component of other combination products. Do not exceed the maximum recommended daily dose of acetaminophen.

U.S. BRAND NAMES — Amidrine [DSC]; Duradrin® [DSC]; Epidrin; Midrin®; Migquin [DSC]; Migratine; Migrazone® [DSC]; Migrin-A [DSC]

PHARMACOLOGIC CATEGORY
Analgesic, Miscellaneous

DOSING: ADULTS
Migraine headache: Oral: 2 capsules to start, followed by 1 capsule every hour until relief is obtained (maximum: 5 capsules/12 hours)

Tension headache: Oral: 1-2 capsules every 4 hours (maximum: 8 capsules/24 hours)

DOSING: ELDERLY — Refer to adult dosing.

DOSING: HEPATIC IMPAIRMENT — Use with caution. Limited, low-dose therapy usually well tolerated in hepatic disease/cirrhosis; however, cases of hepatotoxicity at daily acetaminophen dosages <4 g/day have been reported. Avoid chronic use in hepatic impairment.

DOSAGE FORMS — Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Capsule: Acetaminophen 325 mg, isometheptene mucate 65 mg, dichloralphenazone 100 mg [DSC]
Amidrine [DSC], Duradrin® [DSC], Epidrin, Midrin®, Migquin [DSC], Migrazone® [DSC], Migratine, Migrin-A [DSC]: Acetaminophen 325 mg, isometheptene mucate 65 mg, and dichloralphenazone 100 mg

DOSAGE FORMS: CONCISE
Capsule:
Epidrin, Midrin®, Migratine: Acetaminophen 325 mg, isometheptene 65 mg, and dichloralphenazone 100 mg

GENERIC EQUIVALENT AVAILABLE — Yes

USE — Relief of migraine and tension headache

ADVERSE REACTIONS SIGNIFICANT — Frequency not defined.

Central nervous system: Dizziness (transient)

Dermatological: Rash

CONTRAINDICATIONS — Hypersensitivity to acetaminophen, isometheptene, dichloralphenazone, or any component of the formulation; glaucoma; severe renal disease; hypertension; organic heart disease; hepatic disease; MAO inhibitor therapy

RESTRICTIONS — C-IV

METABOLISM / TRANSPORT EFFECTS — Acetaminophen: Substrate (minor) of CYP1A2, 2A6, 2C9, 2D6, 2E1, 3A4; Inhibits CYP3A4 (weak)

DRUG INTERACTIONS
Antacids: May decrease the excretion of Alpha-/Beta-Agonists. Exceptions: Aluminum Hydroxide. Risk C: Monitor therapy

Anticonvulsants (Hydantoin): May increase the metabolism of Acetaminophen. This may 1) diminish the effect of acetaminophen; and 2) increase the risk of liver damage. Risk C: Monitor therapy

Atomoxetine: May enhance the hypertensive effect of Sympathomimetics. Atomoxetine may enhance the tachycardic effect of Sympathomimetics. Risk C: Monitor therapy

Barbiturates: May increase the metabolism of Acetaminophen. This may 1) diminish the effect of acetaminophen; and 2) increase the risk of liver damage. Risk C: Monitor therapy

Beta-Blockers: May enhance the vasopressor effect of Alpha-/Beta-Agonists (Direct-Acting). Epinephrine used as a local anesthetic for dental procedures will not likely cause clinically relevant problems. Management: Cardioselective beta-blockers and lower doses of epinephrine may confer a more limited risk. Patients who may require acute subcutaneous epinephrine (e.g., bee sting kits) should probably avoid beta blockers. Risk D: Consider therapy modification

Bromocriptine: Alpha-/Beta-Agonists may enhance the adverse/toxic effect of Bromocriptine. Including increased blood pressure, ventricular arrhythmias, and seizure. Risk C: Monitor therapy

Cannabinoids: May enhance the tachycardic effect of Sympathomimetics. Risk C: Monitor therapy

CarBAMazepine: May increase the metabolism of Acetaminophen. This may 1) diminish the effect of acetaminophen; and 2) increase the risk of liver damage. Risk C: Monitor therapy

Carbonic Anhydrase Inhibitors: May decrease the excretion of Alpha-/Beta-Agonists. Exceptions: Brinzolamide; Dorzolamide. Risk C: Monitor therapy

Cholestyramine Resin: May decrease the absorption of Acetaminophen. Effect is minimal if cholestyramine is administered 1 hour after acetaminophen. Risk D: Consider therapy modification

Imatinib: May increase the serum concentration of Acetaminophen. Risk D: Consider therapy modification

Iobenguane I 123: Sympathomimetics may diminish the therapeutic effect of Iobenguane I 123. Risk X: Avoid combination

Isoniazid: May enhance the adverse/toxic effect of Acetaminophen. Risk C: Monitor therapy

MAO Inhibitors: May enhance the vasopressor effect of Alpha-/Beta-Agonists (Direct-Acting). Primarily with oral administration of phenylephrine. Risk D: Consider therapy modification

Peginterferon Alfa-2b: May decrease the serum concentration of CYP2D6 Substrates. Risk C: Monitor therapy

Serotonin/Norepinephrine Reuptake Inhibitors: May enhance the tachycardic effect of Alpha-/Beta-Agonists. Serotonin/Norepinephrine Reuptake Inhibitors may enhance the vasopressor effect of Alpha-/Beta-Agonists. Risk D: Consider therapy modification

Spironolactone: May diminish the vasoconstricting effect of Alpha-/Beta-Agonists. Risk C: Monitor therapy

Sympathomimetics: May enhance the adverse/toxic effect of other Sympathomimetics. Risk C: Monitor therapy

Tricyclic Antidepressants: May enhance the vasopressor effect of Alpha-/Beta-Agonists (Direct-Acting). Risk D: Consider therapy modification

Vitamin K Antagonists (eg, warfarin): Acetaminophen may enhance the anticoagulant effect of Vitamin K Antagonists. Most likely with daily acetaminophen doses >1.3 g for >1 week. Risk C: Monitor therapy

ETHANOL / NUTRITION / HERB INTERACTIONS — Ethanol: Excessive intake of ethanol may increase the risk of acetaminophen-induced hepatotoxicity. Avoid ethanol or limit to <3 drinks/day.

LACTATION — Excretion in breast milk unknown/use caution

BREAST-FEEDING CONSIDERATIONS — Acetaminophen and dichloralphenazone are excreted in breast milk; excretion of isometheptene is not known.

PRICING — (data from drugstore.com)
Capsules (Epidrin)
325-65-100 mg (100): $63.99

Capsules (Isometheptene-APAP-Dichloral)
65-325-100 mg (30): $22.99

Capsules (Migratine)
325-65-100 mg (100): $37.57

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