How does it work?

Perfalgan infusion contains the active ingredient paracetamol,which is a simple painkilling medicine used to relieve mild to moderate painand fever.

Despite its widespread use for over 100 years, we still don'tfully understand how paracetamol works to relieve pain and reduce fever.However, it is now thought that it works by reducing the production ofprostaglandins in the brain and spinal cord.

Prostaglandins are produced by the body in response to injuryand certain diseases. One of their actions is to sensitise nerve endings, sothat when the injury is stimulated it causes pain (presumably to prevent usfrom causing further harm to the area). As paracetamol reduces the productionof these nerve sensitising prostaglandins it is thought it may increase ourpain threshold, so that although the injury remains, we can feel itless.

It is thought paracetamol reduces fever by affecting an area ofthe brain that regulates our body temperature (the hypothalamic heat-regulatingcenter).

Paracetamol is about as effective as aspirin at relieving mildto moderate pain and reducing fever, but unlike aspirin it has noanti-inflammatory effect.

Paracetamol infusion is given in hospital. (An infusion is adrip into a vein.) Paracetamol may be given in this way either because apatient is unable to take medicines by mouth, or because a rapid effect isneeded. This infusion may be given for the short-term relief of moderate pain,particularly following surgery. It may also be used for reducing fever in theshort-term.

What is it used for?

• Short-term relief of moderate pain, particularly following surgery.
• Short-term treatment of fever (pyrexia).

Use with caution in

• Decreased kidney function.
• Decreased liver function.
• Chronic alcoholism.
• Chronic malnutrition.
• Dehydration.

Not to be used in

• Known sensitivity or allergy to any ingredient.
• Severe liver dysfunction.

This medicine should not be used if you are allergic to one orany of its ingredients. Please inform your doctor or pharmacist if you havepreviously experienced such anallergy.If you feel you haveexperienced an allergic reaction, stop using this medicine and inform yourdoctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy orbreastfeeding. However, other medicines may be safely used in pregnancy orbreastfeeding providing the benefits to the mother outweigh the risks to theunborn baby. Always inform your doctor if you are pregnant or planning apregnancy, before using any medicine.

• Oral paracetamol is not known to have any harmful effects when it is used during pregnancy. However, as experience with paracetamol infusion in pregnant women is limited, it should be given with caution to pregnant women and only if the benefits outweigh any possible risks to the foetus. Seek medical advice from your doctor.
• Small amounts of this medicine may pass into breast milk, however there are no known harmful effects when it is used by breastfeeding mothers.

Side effects

Medicines and their possible side effects can affect individualpeople in different ways. The following are some of the side effects that areknown to be associated with this medicine. Just because a side effect is statedhere does not mean that all people using this medicine will experience thator any side effect.

• Skin rash.
• General feeling of being unwell (malaise).
• Decreased blood pressure.
• Raised liver enzymes.

The side effects listed above may not include all of the sideeffects reported by the medicine'smanufacturer.For moreinformation about any other possible risks associated with this medicine,please read the information provided with the medicine or consult your doctoror pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while being treated with this one, to ensure that the combination is safe.

Other medicines that contain paracetamol must not be used incombination with this medicine.

Probenecid may increase the blood level of this medicine. Alower dose may be needed if it is used in combination withprobenecid.

Salicylamide may prolong the amount of time the paracetamolstays in the body.

Regular use of maximum doses of paracetamol for longer than fourdays may increase the anti-blood-clotting effect of anticoagulant medicinessuch as warfarin, which could increase the risk of bleeding associated withthese medicines. This effect does not occur with occasional painkilling dosesof paracetamol. If paracetamol is used at the maximum dose for longer than fourdays in people taking anticoagulants such as warfarin, increased monitoring ofblood clotting times (INR) should be performed. The increased monitoring shouldbe performed while the paracetamol is being used, and for a week after it hasbeen stopped. Your doctor may need to adjust your anticoagulant dose on thebasis of the results.

Other medicines containing the same active ingredient

Paracetamol tablets, capsules, caplets, soluble tablets,suspension and suppositories are also widely available without brand names, ieas thegeneric medicine.

NB. Paracetamol is known as acetaminophen in the USA and someother countries.