100 Migraine Drugs, A to Z: dichloralphenazone

Dichloralphenazone is one of three ingredients in the headache drug, Midrin. The other two ingredients are isometheptene, a drug that constricts blood vessels and acetaminophen. Midrin actually is a combination of four drugs because dichloralphenazone is broken down in the body into chloral hydrate, which is an old sedative hypnotic drug used for insomnia and antipyrine, a non-steroidal anti-inflammatory pain medicine.

Midrin is a very old drug which was introduced before the 1962 Congressional act that required rigorous clinical trials for the FDA approval. It has been marketed for both migraine and tension-type headaches. The directions, which are not based on any research studies, recommend: “For relief of migraine headaches: The usual adult dosage is two capsules at once, followed by one capsule every hour until relieved, up to 5 capsules within a twelve hour period. For relief of tension headache: The usual adult dosage is one or two capsules every four hours up to 8 capsules a day.”

Several small studies of Midrin have been published. One double-blind study, published in 1976 involved 43 patients who were rotated from Midrin to acetaminophen and then, placebo. Midrin was found to be more effective. Another double-blind study, published in 2001 compared Midrin with sumatriptan (Imitrex), 100 mg and found them to be equally effective.

I do come across an occasional patient for whom Midrin is more effective than the triptans or any other drug without causing any side effects. Or, sometimes the side effect of sedation is preferable to having a migraine that does not respond to any medication.

Because Midrin contains a sedative medications, which is potentially addictive, it is considered to be a controlled drug. The supply of Midrin has been very inconsistent because it lacks an official FDA approval and because very few doctors prescribe it. When it is not available from a pharmaceutical manufacturer some doctors order it from a compounding pharmacy, which makes Midrin by mixing the three individual ingredients by hand in small batches.