Hepatotoxicity - Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen at doses that exceed 4,000 milligrams per day, and often involve more than one acetaminophen-containing product. The excessive intake of acetaminophen may be intentional to cause self-harm or unintentional as patients attempt to obtain more pain relief or unknowingly take other acetaminophen-containing products. The risk of acute liver failure is higher in individuals with underlying liver disease and in individuals who ingest alcohol while taking acetaminophen.
Instruct patients to look for acetaminophen or APAP on package labels and not to use more than one product that contains acetaminophen. Instruct patients to seek medical attention immediately upon ingestion of more than 4,000 milligrams of acetaminophen per day, even if they feel well.
Hypersensitivity/Anaphylaxis – There have been post-marketing reports of hypersensitivity and anaphylaxis associated with the use of acetaminophen. Clinical signs included swelling of the face, mouth, and throat, respiratory distress, urticaria, rash, pruritus, and vomiting. There were infrequent reports of life-threatening anaphylaxis requiring emergency medical attention. Instruct patients to discontinue Isometheptene, Caffeine, and Acetaminophen Tablets immediately and seek medical care if they experience these symptoms. Do not prescribe Isometheptene, Caffeine, and Acetaminophen Tablets for patients with acetaminophen allergy.
Based on a review of this drug (isometheptene mucate), the National Academy of Sciences- National Research Council and/or other information, FDA has classified the other indication as “Possibly” effective in the treatment of migraine headache. Final classification of less than effective indication requires further investigation.
Isometheptene Mucate is a white crystalline powder having a characteristic aromatic odor and bitter taste. It is an unsaturated aliphatic amine with sympathomimetic properties. Isometheptene mucate has the following structural formula:
Figure 1: Isometheptene mucate
(C9H19N)2•C6H10O8 M.W. 492.65
Caffeine is 1H-Purine-2,6-dione, 3,7-dyhydro-1,3,7-trimethyl-. It has the following structural formula:
Figure 2: Caffeine
C8H10N4O2 M.W. 194.19
Acetaminophen, a non-salicylate, occurs as a white, odorless, crystalline powder, possessing a slightly bitter taste. Acetaminophen is Acetamide, N-(4-hydroxyphenyl)-. It has the following structural formula:
FOR RELIEF OF MIGRAINE HEADACHE: The usual adult dosage is two tablets at once, followed by one tablet every hour until relieved, up to 5 tablets within a twelve hour period.
FOR RELIEF OF TENSION HEADACHE: The usual adult dosage is one or two tablets every four hours up to 8 tablets a day.
FOR RELIEF OF MIGRAINE HEADACHE: The usual adult dosage is one or two caplets at once, followed by one caplet every hour until relieved, up to 5 caplets within a twelve hour period.
FOR RELIEF OF TENSION HEADACHE: The usual adult dosage is one or two caplets every four hours up to 8 caplets a day.