Pralidoxime (Injection)

Pralidoxime is an intravenous medication used in certain cases of pesticide poisoning and overdose.

Overview

Pralidoxime is a drug which is administered via injection to patients who are suffering from certain types of poisoning.

Some chemicals, pharmaceuticals, and drugs can cause muscle weakness and paralysis if taken in large quantities. Pralidoxime is administered in order to reverse this muscle weakness. It serves as an antidote against certain types of pesticides, as well as working in the event of an overdose of medication used to treat muscle disorders.

It will not work against all pesticides but it is an effective treatment in many cases, as long as it is administered very soon after the poisoning has occurred.

Pralidoxime is given to patients as soon as possible after they begin to exhibit signs of overdose or poisoning. It is given intravenously either straight into the muscle or into a vein. It is important that the medication is given slowly rather than in one go in an injection. It may take up to half an hour to complete one dose of Pralidoxime and some patients may require several doses to be given over a number of days.

Pralidoxime is a medication which is usually administered by doctors in a hospital setting. Patients who receive treatment with Pralidoxime are usually kept under observation in hospital for as long as 72 hours to ensure that the medication is doing its job and that the poisoning or overdose has not caused any lasting damage. While under observation, the patient's breathing, kidney function, oxygen levels, blood pressure and other vital signs will be closely monitored.

Pralidoxime can be used to treat poisoning by nerve gas. It is therefore often carried by military personnel. For use under these circumstances, the medication comes in an easy-to-use auto-injector which military personnel can use to treat themselves or others.

Conditions treated

  • Pesticide poisoning
  • Nerve gas poisoning
  • Overdose

Type of medicine

  • Antidote

Side Effects

As with most medication, the use of Pralidoxime comes with some risk of side effects. When a doctor decides on a particular course of treatment, they will weight up the benefits and the risks of using that particular medication. If they decide to prescribe, it will be because they believe that the overall benefit of the medication is greater than the risk posed by any side effects.

Side effects are unwanted symptoms caused as a result of taking a certain medication, which have nothing to do with the original condition that the patient is being treated for.

The most common side effects which are experienced by patients who have been given Pralidoxime are drowsiness, headaches and nausea. Not all patients who take the drug experience these side effects, but these are the most prevalent. They can usually be managed and whilst they may cause temporary discomfort for the patient, they are not a cause for alarm. Patients experiencing these side effects should only seek medical attention if the symptoms are particularly severe or long-lasting.

Occasionally, Pralidoxime will cause more serious side effects for patients, which may be of concern to doctors. As patients taking Pralidoxime will be kept under observation throughout the course of the treatment, they will be being closely monitored. Healthcare professionals will therefore be on hand to manage any more serious side effects. Patients should take care to advise their doctor or nurse if they experience any of the following after being treated with Pralidoxime:

  • Dizziness
  • Problems with eyesight e.g. Blurred vision or seeing double
  • Changes in vision
  • Difficulty in being able to focus the eyes
  • Severe pain at the site of the injection
  • Fast or irregular heartbeat
  • Muscle weakness
  • Muscle stiffness
  • Labored breathing
  • Rapid breathing, sometimes combined with dizziness
  • Numbness and tingling in the extremities

If patients experience any of the symptoms listed above, they should let their doctor or nurse know immediately. These symptoms are less easy to manage, and could cause harm in their own right. It may be that they require further treatment or that the doctors will monitor you more closely in order to make sure that the symptoms do not escalate and that they will not cause any lasting damage in their own right.

Dosage

The dose of Pralidoxime prescribed to a patient will vary from patient to patient. Doctors will prescribe the dose of medication which they believe will be the most effective given the patient's age, weight, general health condition and the quantity of poison or excess medication they have consumed. The amount of medicine prescribed will also depend on its strength as Pralidoxime is available in different strengths of solution.

In most circumstances, doctors will use the following doses as guidelines, however they will change the dose as required.

Usual adult dose for poisoning by organic phosphorus pesticides

1 “ 2 grams is injected into a vein in a saline solution over the course of 15-30 minutes via an IV drip. This dose is then likely to be repeated an hour after the first one, with further doses every 8 “ 12 hours if necessary.

Usual adult dose for treating cases of nerve gas poisoning

A dose of 600mg is injected straight into the muscle. This dose is likely to be repeated at 15 minute intervals if required.

Usual adult dose for muscle weakness medication overdose (Myasthenia gravis)

An initial dose of 1-2 grams is injected into a vein. The doctor will then continue to inject doses of 250mg every five minutes as required.

Pralidoxime comes in two different forms: a vial of liquid medication and pre-loaded in an auto-injector device. The vial is what is used by doctors in hospital settings. In these situations there is no need for the patient to treat themselves, and doctors need to be able to adjust the doses as necessary according to the differences between patients. The auto-injector is an automatic injection device which allows Pralidoxime to be administered away from a hospital setting. This is mainly used by the military to treat cases of nerve gas poisoning whilst out in the field.

Auto-injectors are very easy to use, allowing patients to administer the medication to themselves if necessary. It is

1) When ready to use the medication, the safety cap will need to be removed.
2) Position the black tip of the auto-injector against the thigh, with the device at a 90 degree angle to the skin
3) Press down hard into the thigh in order to trigger the automatic function of the auto injector. Hold it there for several seconds to allow all of the medication to be injected.
4) Remove the device and replace the safety cap
5) Massage the site of the injection for at least 10 seconds to stimulate the flow of medication and to relive the pain
6) Dispose of the auto injector according to the instructions on the label

Interactions

Whenever a patient receives more than one form of medication at the same time, especially where the treatments are for multiple conditions, there is always the possibility of interactions between drugs. When combined, two or more medicines can begin to work differently. Interactions between different drugs can have an effect on the way in which each of the drugs behave. They can increase the prevalence and severity of side effects, cause new conditions or symptoms or prevent the medication from being as effective.

In order to avoid interactions between different pharmaceuticals, it is important for patients to keep an up-to-date and accurate list of all of the medications, supplements and home remedies that they are currently taking. This list should include all of the medication they have been prescribed, along with over-the-counter medications, non-prescription medicines, legal and illegal drugs and vitamins and dietary supplements. This list will help the doctor, pharmacist or healthcare professional to

This list should be kept somewhere accessible. Pralidoxime is a drug which is usually administered in an emergency, under time-sensitive conditions. Having a list of drugs you are taking nearby and accessible will greatly help the doctors to avoid interactions.

This is not a fully comprehensive list, but detailed below are the most common drugs which are known to interact with Pralidoxime:

  • Aminophylline
  • Tranquilizers (e.g. chlorpromazine, trifluperazine, fluphenazine, thioridazine, perphenazine, prochlorperazine)
  • Opiates
  • Barbituates (eg. Butabarbital, secobarbital, pentobarbital, phenobarbital)
  • Morphine
  • Atropine
  • Theophylline
  • Reserpine

Patients who are prescribed with Pralidoxime should take care to let their doctor know if they are already taking any of the drugs in the list above.

Warnings

Pralidoxime is an antidote used to reverse the effects of poisons and overdoses. It is therefore used in emergency situations and is quite often instrumental in preserving a patient's life or in maintaining their quality of life. In many situations, this will mean that the benefits of using this medication outweigh any of the risks associated with it.

Pregnancy

The full effect of treatment with Pralidoxime on an unborn baby is not known. There have not been enough studies in humans to determine the level of risk of using Pralidoxime during pregnancy.

Breastfeeding

It is not known whether Pralidoxime can pass from mother to baby through breast milk. Patients should consult their doctor about breastfeeding after receiving Pralidoxime treatment.

Storage

Pralidoxime is a medication which is only given to patients by qualified healthcare professionals in a hospital setting. It will therefore not be necessary for civilian patients to store the drug at home. In the hospital, vials of Pralidoxime should be stored in a secure room. The vials should remain away from excess heat, moisture and sunlight. They do not need to be refrigerated.

Pralidoxime auto-injectors should be stored at 25ºC (77ºF) wherever possible. The auto=injectors should be protected from excess heat, moisture and direct sunlight. They are safe to take on excursions where the temperature will be somewhere between 15ºC and 30ºC (between 59ºF and 86ºF). The auto injectors should be kept somewhere accessible in case of an emergency.

As with all medications, Pralidoxime should be stored in the container in which it was supplied. The medication should be clearly labelled at all times in order to avoid any potential confusion about the contents. If the medication is issued with instructions about how to use it, these instructions should be kept close by at all times. Medication should not be moved into a different container for storage and it should be kept out of the way of animals and children.

Summary

Pralidoxime is a powerful antidote which is used to treat patients who have been exposed to certain chemicals. It is used to counteract the muscle weakness and paralysis which can be caused by pesticide poisoning, nerve gas poisoning and overdoses of medication for come muscular diseases and conditions. It is always administered intravenously, either by an injection into the muscle or through an intravenous drip into a vein.

For civilian patients, Pralidoxime is only given in hospital conditions. The doses are set by the doctors who can continue to repeat doses if needed. Patients who have been given Pralidoxime treatment are closely monitored for up to 3 days in order to keep a close eye on their condition and on the functioning of the drug. The dose of Pralidoxime prescribed will vary from patient to patient according to their age, weight, condition and their responsiveness to the treatment. In some cases, doses may be repeated at intervals which are just 5 minutes apart.

Pralidoxime is also used as an effective antidote to nerve gas poisoning. It is therefore carried by military personnel at risk of such an attack. In these instances, the Pralidoxime is carried in the form of an auto-injector which allows military medics to administer doses outside of a hospital setting. It also allows the option of self-administering the medication if necessary.