Edrophonium (Injection)

Overview

When patients are suffering from myasthenia gravis, or extreme muscle weakness, the skeletal muscles are most noticeably affected. Responsible for moving parts of the body and breathing, these muscles should be working optimally in order for the patient to be functioning effectively.

As myasthenia gravis is an autoimmune disease, it is chronic in nature. Whilst treatments aren't able to cure the condition, they can help to manage it appropriately. Immunosuppressive agents, for example, may be used to help prevent the body's tissues from being attacked or inflamed. In addition to this, Edrophonium can be given to reduce the muscle weakness.

In patients with myasthenia gravis, the nicotinic acetylcholine receptors are impeded or destroyed. As an acetylcholinesterase inhibitor, Edrophonium blocks acetylcholine enzymes and enables acetylcholine to remain in the patient's system for longer. By doing so, Edrophonium can help to reduce the muscle weakness experienced by the patient and relieve their symptoms.

Once myasthenia gravis is being treated effectively, it should not be life-threatening for the patient. However, the condition can affect the patient's breathing so it's vital that treatment is commenced as quickly as possible. If a myasthenia crisis occurs, it could leave the patient in a life-threatening or critical condition. By administering Edrophonium, alongside emergency breathing assistance, physicians can help to reduce muscle weakness and enable to patient to breathe more easily, thus alleviating any life-threatening symptoms.

Although other muscular conditions may have similar effects to myasthenia gravis, their causes are different. Edrophonium can, therefore, be used to determine whether the patient is suffering from myasthenia gravis or an alternative condition, such as Lambert-Eaton myasthenic syndrome or from a cholinergic crisis.

In addition to this, Edrophonium can be used to reverse the effects of muscle relaxants. If the patient has consumed too many muscle relaxants and is experiencing symptoms of an overdose, Edrophonium can help to reduce the muscle weakness they're experiencing. Also, Edrophonium may be used to alleviate neuromuscular blocks following an operation or surgical procedure.

Conditions Treated

  • Myasthenia gravis
  • Muscle relaxant overdose
  • Post-operative neuromuscular block reversal

Type Of Medicine

  • Anticholinesterase agent

Side Effects

Before being treated with Edrophonium, physicians may warn patients about some of the side-effects they could experience. Although these may be relatively mild, it can put the patient's mind at ease if they know what to expect following treatment. If patients notice these side-effects, for example, they may not require any additional medical treatment:

  • Stomach or abdominal cramps
  • Diarrhea
  • Constricted pupils (black part of the eye)
  • Hoarseness
  • Double vision
  • Increased salivation
  • Nausea
  • Muscle weakness
  • Redness of the white part of the eyes
  • Redness of the inside of the eyelids
  • Watering of the eyes
  • Vomiting
  • Sore throat

If patients are affected by these side-effects, they tend to be relieved as the medication is absorbed by the body. Patients may notice them fairly quickly following treatment but they should obtain relief from them soon after. If they are severe, however, or if they are prolonged, patients should always seek medical help. Although medical intervention may not be required, healthcare practitioners may be able to advise the patient how their side-effects can be reduced or minimized.

In addition to this, patients will need to seek medical assistance if they experience any of the following side-effects after being treated with Edrophonium:

  • Chest discomfort or pain
  • Unusual tiredness
  • Dizziness
  • Trouble speaking
  • Fainting
  • Difficulty breathing
  • Irregular, slow or fast heartbeat
  • Slurred speech
  • Increased frequency of urination
  • Seizures
  • Increased sweating
  • Dizziness, fainting or lightheadedness
  • Muscle twitches which are visible under the skin
  • Loss of bladder control

Although the above symptoms may not be indicative of a problem with the treatment, they should be assessed by a medical professional. Patients should also obtain medical advice if they experience any side-effects which have not been listed here.

Dosage

Available in solution format, Edrophonium is typically administered via an intramuscular injection or an injection into the patient's vein.

If patients are being tested for myasthenia gravis, a relatively small amount of Edrophonium may be administered over a period of 15-45 seconds. Doctors will then observe the patient's reaction to aid in their diagnosis. Patients may exhibit signs of muscle twitching, increased muscle weakness, stomach cramps, sweating, nausea and/or vision changes. Additional medications can be given to alleviate these symptoms, if necessary.

Generally, 2mg of Edrophonium will be used to test for myasthenia gravis but this may be increased to 8mg if the patient doesn't exhibit a reaction to the medicine.

When physicians a reversing a neuromuscular block, however, 10mg of Edrophonium may be given intravenously over a period of 30-45 seconds. Although this can be increased if necessary, the maximum dose of Edrophonium is normally 40mg.

When carrying out diagnostic tests for myasthenia gravis, physicians will determine what dose of medication is appropriate for the patient. It may be necessary for the test to be carried out more than once so this may affect their physician's dosage instructions.

However, Edrophonium will be administered by a healthcare practitioner so patients will not be required to calculate or administer their own dose of Edrophonium.

Potential Drug Interactions

Using Edrophonium in conjunction with the following medications is not usually recommended but may be appropriate in some cases:

  • Bupropion
  • Donepezil

If doctors prescribe Edrophonium alongside either of these medications, they may alter the patient's dose to prevent an interaction occurring.

Interactions can also occur between prescribed medicines, over-the-counter formulations, supplements and vitamins. Patients should, therefore, inform their physician if they have taken any of these substances before they are treated with Edrophonium. Furthermore, patients should obtain medical advice before taking any other medicines, vitamins and/or supplements after receiving an Edrophonium injection.

Warnings

If patients have existing medical conditions, it may affect the use of Edrophonium. Patients should discuss their medical history with their physician before receiving treatment. The following conditions may prevent Edrophonium from being used on the patient:

  • Kidney blockage
  • Bowel blockage
  • Bladder blockage
  • Allergy to sulphites
  • Slow heartrate (Bradycardia)
  • Asthma and/or breathing problems
  • Heart rhythm problems

Edrophonium may be given to patients who are pregnant but should be prescribed cautiously. It is possible that the medication may pose a risk to an unborn fetus and Edrophonium should, therefore, only be administered if the benefits outweigh the risks associated with the medicine.

If patients become pregnant after receiving treatment with Edrophonium, they should consult their physician for advice. As myasthenia gravis is a chronic condition, patients should discuss pregnancy with their physician so that an alternative treatment regime can be put in place if or when the patient does become pregnant.

Currently, it is not known whether Edrophonium can be passed to infants via breastfeeding. Due to this, patients are normally advised not to breastfeed if they have been treated with this medication. Patients should obtain medical advice from their physician before breastfeeding if they have been treated with Edrophonium.

When patients are being treated with Edrophonium, they should be monitored thoroughly. Healthcare practitioners will need to assess the patient's response to the medicine, particularly if it is being used for diagnostic purposes.

Although Edrophonium is normally stored in vials, a rubber stopper may be used to keep the medication is a contained, controlled environment. If patients are allergic to rubber or latex, the medication may cause them to exhibit an allergic reaction. Patients should notify their physician if they have a known latex or rubber allergy before Edrophonium is administered.

In addition to this, patients should inform their doctor if they have any other known allergies. In some cases, Edrophonium may cause patients to exhibit an allergic reaction which may include anaphylaxis. As this can be life-threatening, it's vita' that patients are treated immediately. Symptoms may include:

  • Wheezing
  • Difficulty breathing
  • Hives
  • Increased heartrate
  • Hoarseness
  • Swelling of the face, lips, throat, lips and/or tongue
  • Itching

Storage

Normally, Edrophonium is stored in glass vials or ampoules until it is ready to be used. Unless the manufacturer instructs otherwise, these should be kept at a room temperature between 15-30?C (59-86? F). In addition to this, Edrophonium should be kept away from direct light whilst it is being stored.

However, Edrophonium is administered by a healthcare practitioner in a clinical setting. Patients should not, therefore, need to store, prepare or dispose of the medication themselves.

Summary

Useful in both the diagnosis and treatment of myasthenia gravis, Edrophonium is an important medication when the condition is suspected. As well as causing debilitating symptoms, a myasthenia crisis can place patients in a life-threatening condition. By administering Edrophonium in appropriate doses, however, physicians can reverse the effects of the muscle weakness and, in turn, enable patients to breathe without restriction.

Although Edrophonium is essential for treating myasthenia gravis, it is also a much-used post-operative medicine. If patients have been given a neuromuscular block prior to surgery being performed, Edrophonium can be administered in order to reverse the effects of the block and minimize the patient's post-operative discomfort.

Due to its varied uses, Edrophonium is an essential medication and is routinely used in hospitals and clinics across the US.