Amidrine, Duradrin, Epidrine, or Midrin, is a combination of acetaminophen, dichloralphenazone

Dichloralphenazone

Dichloralphenazone is a 1:2 mixture of antipyrine with chloral hydrate. In combination with paracetamol and isometheptene, it is the active ingredient of medications for migraine and vascular headaches, including Epidrin and Midrin. Performance impairments are common with this drug and caution is...

, and isometheptene

Isometheptene

Isometheptene is a sympathomimetic amine sometimes used in the treatment of migraines and tension headaches due to its vasoconstricting properties, that is, it causes constriction of blood vessels...

 used mostly to treat headache

Headache

A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...

s.

Components

• Paracetamol (acetaminophen) is a common over-the-counter pain reliever and fever
  Fever
  Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
  
   reducer.

• Dichloralphenazone is a mild sedative
  Sedative
  A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....
  
   owing primarily to its hydrolysis product, chloral hydrate
  Chloral hydrate
  Chloral hydrate is a sedative and hypnotic drug as well as a chemical reagent and precursor. The name chloral hydrate indicates that it is formed from chloral by the addition of one molecule of water. Its chemical formula is C2H3Cl3O2....
  
  . Chloral hydrate, a schedule C-IV controlled substance, is a sedative
  Sedative
  A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....
  
  /hypnotic
  Hypnotic
  Hypnotic drugs are a class of psychoactives whose primary function is to induce sleep and to be used in the treatment of insomnia and in surgical anesthesia...
  
   drug that acts on the central nervous system to produce relaxation and decrease emotional stimuli that influence the perception of pain associated with headache.

• Isometheptene is a vasoconstrictor
  Vasoconstriction
  Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
  
  , a drug that causes constriction (narrowing) of cerebral blood vessels.

The pathophysiology of vascular headaches, especially migraine

Migraine

Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...

, is thought to be related to dilation of these cerebral blood vessels, so drugs that act to constrict them are used in the treatment of these problems.

Common application

This drug is commonly used in the treatment of migraine

Migraine

Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...

 headaches and is currently available in the United States and United Kingdom by prescription only.

One study has shown that this drug may work better than Imitrex for treating migraines.
This drug has been discontinued by Caraco Pharmaceuticals as of 2009.