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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Infomed Drug Guide

The information contained in the "Infomed Drug Guide" is aimed at medical professionals and students of medicine and pharmacology. All of the data has been carefully compiled and checked, however, errors may occur. These errors may also result due to changes that have taken place in the medical sciences since the publication of the Drug Guide in 1994/2008, and cannot be excluded. In case of doubt, readers are encouraged to confirm the information contained herein with other sources before a drug is prescribed. Non-professionals should be aware that the "Infomed Drug Guide" does not seek to replace professional medical advice and/or treatment. Neither Infomed, nor the authors, claim that the information is in every respect accurate or complete. As a result, neither can be held responsible for any errors or omissions, or for any consequences resulting from the use of such information.

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