What is a Patient Information Leaflet and why is it useful?

The Patient Information Leaflet (PIL) is the leaflet included in the pack with a medicine. It is written for patients and gives information about taking or using a medicine. It is possible that the leaflet in your medicine pack may differ from this version because it may have been updated since your medicine was packaged.

Below is a text only representation of the Patient Information Leaflet. The original leaflet can be viewed using the link above.

The text only version may be available in large print, Braille or audio CD. For further information call emc accessibility on 0800 198 5000. The product code(s) for this leaflet is: PL 01883/0063.

Physeptone 25mg/ml Solution for Injection


Physeptone 25mg/ml Solution for Injection

Methadone Hydrochloride

(This medicine will be referred to as Physeptone Solution for Injection in this leaflet)

Read all of this leaflet carefully before you are given Physeptone Solution for Injection because it contains important information for you.

  • Keep this leaflet. You may need to read it again
  • If you have any further questions, ask your doctor or nurse
  • If you get any side effects, talk to your doctor or nurse. This includes any possible side effects not listed in this leaflet. See section 4.

What is in this leaflet

1. What Physeptone Solution for Injection is and what it is used for
2. What you need to know before Physeptone Solution for Injection is given
3. How Physeptone Solution for Injection is given
4. Possible side effects
5. How to store Physeptone Solution for Injection
6. Contents of the pack and other information

1. What Physeptone Solution for Injection is and what it is used for

The active ingredient of this medicine, Methadone Hydrochloride, is a synthetic opiate (a morphine- like drug) used in the treatment of addiction in order to reduce withdrawal symptoms.

2. What you need to know before Physeptone Solution for Injection is given

You should not be given Physeptone Solution for Injection if:

  • You are allergic to methadone hydrochloride or any of the ingredients of this medicine ( listed in section 6).
  • You are not already receiving physeptone. This is a high concentration and is not suitable for people who have not taken physeptone before.
  • You have any problem with your breathing or any chronic lung disease such as chronic obstructive pulmonary disease
  • You are having an asthma attack. Do not take your dose until you have completely recovered.
  • You are taking, or have stopped taking within the last two weeks, a type of medicine known as monoamine oxidase inhibitors (MAOIs) which are used to treat depression
  • You have pheochromocytoma, a tumour of the adrenal glands.
  • You have a bowel disorder known as paralytic ileus
  • You have loss of consciousness

Physeptone Injection is not suitable for children under the age of 16 years.

If any of the conditions above apply to you, please consult your doctor.

Warnings and precautions

Talk to your doctor or pharmacist before taking Physeptone Solution for Injection

  • because it can be addictive.
  • only use the dose prescribed for you by your doctor because higher doses could be fatal. Without you knowing, the levels of the drug can build up in your body and affect your breathing, causing drowsiness and possible loss of consciousness.
  • if you have increased pressure on the brain or have just had a head injury.
  • if you are suffering from acute alcoholism.
  • if you are suffering from mental illness brought on by an infection
  • if you have liver problems
  • if you have kidney problems
  • if you have problems with your bile duct
  • if you suffer from an enlarged prostate gland (in men) or have difficulty passing urine
  • if you have an under-active thyroid or adrenal gland.
  • if you have low blood pressure
  • if you are in a state of severe shock
  • if you are very run down and feeling weak
  • if you have bowel disease, such as Crohn’s disease or ulcerative colitis
  • if you suffer from convulsions (fits)
  • if you are a child. Even at low doses Physeptone is a special hazard to children if taken accidentally. Children under 6 months, particularly newborns, may be more sensitive to breathing difficulties than adults
  • if you are elderly
  • if you have myasthenia gravis (a disorder that causes extreme muscle fatigue)
  • if you suffer from certain types of heart disorders. These types of heart disorder are usually confirmed after an electrocardiogram (ECG) has been performed and may be more likely to occur with the following:
    • if you have, or have had in the past any heart disorder or disease.
    • if you have liver disease
    • if other members of your family have died suddenly from unexplained causes.
    • if you have reduced blood levels of potassium or magnesium
    • if you take particular medicines while you are taking Physeptone; please read the section ‘Taking/using other medicines’.
    • if you are taking high doses of Physeptone (e.g. more than 100 mg per day).

Your doctor may wish to monitor you by doing an ECG either before you start taking Physeptone and/or during treatment.

Injections may be painful; check the site of injection regularly for swelling, reddening or itching.

Always tell your doctor or nurse about any of these conditions or medicines before having your treatment

Other medicines and Physeptone Solution for Injection

Tell your doctor or pharmacist, if you are taking, have recently taken, or might take any other medicines.

  • Medicines used to treat addiction e.g. naltrexone, naloxone and buprenorphine
  • Cimetidine (a medicine used to treat stomach ulcers)
  • Metoclopramide or domperidone (medicines used to stop you feeling or being sick)
  • Drugs used to treat epilepsy (e.g. phenytoin)
  • Mexiletine, a drug used to treat heart irregularities
  • Antibiotics (medicines used to treat bacterial infections e.g. ciprofloxacin, rifampicin,erythromycin and rifabutin)
  • Antifungals (medicines used to treat fungal infections) e.g itraconazole and fluconazole
  • Medicines that makes urine more acidic such as ammonium chloride Antiviral drugs including some medicines used to treat HIV e.g. nevirapine, zidovudine, efavirenz, nelfinavir, ritonavir and abacavir
  • Medicines used to treat depression known as tricyclic antidepressants, such as amitriptyline, and selective serotonin re-uptake inhibitors, such as fluvoxamine
  • Medicines used to treat severe depression known as monoamine oxidase inhibitors (MAOIs)
  • CNS depressants (medicines that act on the brain and cause drowsiness or sleepiness) e.g benzodiazepines, chloral hydrate and chlormethiazole
  • Other opioid type drugs e.g. morphine
  • Medicines used to treat sleep disorders e.g. sodium oxybate
  • Pentazocine (a pain killer)
  • Medicines used to help you relax (tranquillisers)
  • Cyclizine (an antihistamine used to treat nausea, vomiting and dizziness)

Other medicines you may be taking can also affect the heart. You must tell your doctor about any other medicines that you are taking as they may be dangerous if they are taken with Physeptone. In these situations your doctor may decide that it is necessary to monitor your heart with an electrocardiogram (ECG) at the start of treatment to ensure that these effects do not occur.

Concomitant use of Physeptone Solution for Injection and sedative medicines such as benzodiazepines or related drugs increases the risk of drowsiness, difficulties in breathing (respiratory depression), coma and may be life-threatening. Because of this, concomitant use should only be considered when other treatment options are not possible.

However if your doctor does prescribe Physeptone Solution for Injection together with sedative medicines the dose and duration of concomitant treatment should be limited by your doctor.

Please tell your doctor about all sedative medicines you are taking, and follow your doctor’s dose recommendation closely. It could be helpful to inform friends or relatives to be aware of the signs and symptoms stated above. Contact your doctor when experiencing such symptoms.

Physeptone Solution for Injection with food, drink and alcohol

You must not drink alcohol whilst you are being treated with Physeptone Solution for Injection as this could cause serious side effects.

You are advised not to drink grapefruit juice whilst you are being treated with Physeptone Solution for Injection as it could cause an overdose.


There is not enough evidence of safety of physeptone in pregnancy; for the benefit of both you and your baby, you should seek the advice of a doctor with appropriate experience so specialized care can be arranged. Babies born to mothers taking physeptone may suffer withdrawal symptoms.


Physeptone gets into breast milk; breast-fed infants may develop their own physical dependence on it. If breast feeding is considered, your dose of Physeptone Solution for Injection should be as low as possible and you should watch your baby closely for any signs of excessive sleepiness. Remember your baby could suffer withdrawal symptoms if you either stop taking physeptone or stop breast feeding suddenly. Talk to your doctor so you and your baby get the care required where necessary.

Driving and using machines

The ability to drive or use machines may be severely affected during and after treatment with physeptone. You must not drive or use machinery until you are told that you can do so by your doctor.

The medicine can affect your ability to drive as it may make you sleepy or dizzy.

  • Do not drive while taking this medicine until you know how it affects you
  • It is an offence to drive if this medicine affects your ability to drive
  • However, you would not be committing an offence if :
    • The medicine has been prescribed to treat a medical or dental problem and
    • You have taken it according to the instructions given by the prescriber or in the information provided with the machines and
    • It was not affecting your ability to drive safely

Talk to your doctor or pharmacist if you are not sure whether it is safe for you to drive while taking this medicine.

3. How Physeptone Solution for Injection is given

Physeptone Solution for Injection will be given to you by a doctor in a hospital. It will be given under the skin or into a muscle.


For the treatment of drug addiction:

The recommended initial dose is 10-20 mg a day. The dose will be slowly increased by 10-20mg until you show no signs of withdrawal or intoxication. The dose may need to be over 100mg daily (depending of the level of tolerance you have to Physeptone) in order to prevent withdrawal symptoms.

The elderly or ill:

If you are elderly or ill, your doctor will only prescribe repeated doses with caution.

Use in children:

Physeptone Solution for Injection should not be used in children under the age of 16 years.

If you think you have been given too much Physeptone Solution for Injection

The medicine will be given to you by your doctor so it is unlikely you will receive too much. If you are concerned about your treatment, please talk to your doctor. If you are given too much Physeptone Solution for Injection, you can experience the following:

  • Difficulty in breathing
  • Extreme sleepiness, fainting or coma
  • Pin point pupils
  • Muscle weakness
  • Cold and clammy skin
  • Slow heartbeat, low blood pressure, heart attack or shock. In severe cases death may occur.

In the event of overdose you should seek medical assistance immediately even if you feel well as you may be suffering physeptone poisoning.

If you stop having Physeptone Solution for Injection

If you stop having Physeptone Solution for Injection suddenly you may experience withdrawal symptoms. If you need to stop having Physeptone Solution for Injection your doctor will gradually reduce the dose.

4. Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them.

Stop taking this medicine and see a doctor straightaway if you have any of the following:

  • Heart problems. The signs of this may include changes in the way your heart beats, such as it beating faster or missed heart beats, breathing difficulties and dizziness
  • If your breathing become slow and shallow.

Keep taking this medicine but tell your doctor straightaway if you get the following side effect:

  • Worsening of the pressure inside your head if you already have this condition following an injury to your brain or brain disease.

Other side effects:

  • Dizziness
  • Nausea (feeling sick) or vomiting (being sick)
  • Headaches
  • Pain and skin irritation at the site of injection
  • Rashes or itching
  • Sweating
  • Reduced blood pressure (you may feel dizzy on standing up)
  • Small pupils
  • Confusion, mood changes
  • Fast, slow beating of the heart, a feeling of trembling in the heart
  • Facial flushing
  • Spasms of the tubes from the gall bladder or urinary bladder
  • Difficulty passing urine
  • A reduction in sex drive
  • Feeling cold (fall in body temperature)
  • Redness, swelling and hardening of the skin at the site of injection
  • Painful menstruation cramps or absence of period
  • Constipation
  • High blood levels of the hormone prolactin
  • Hearing or seeing things that are not there (hallucinations)

You can become dependent on physeptone.

In the case of serious side effects, patients should be kept conscious wherever possible and an airway established; artificial respiration may be necessary.

Repeated intravenous administration or appropriate antidote medication (nalorphine or levallorphine) may be required if there is evidence of significant breathing difficulty. Oxygen, intravenous fluids, drugs to increase blood pressure and other supportive measures should be employed as necessary according to the severity of the side effect.

Reporting of side effects

If you get any side effects, talk to your doctor or pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via Yellow Card Scheme. Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store Physeptone Solution for Injection

Keep this medicine out of the sight and reach of children.

Do not use this medicine after the expiry date which is stated on the ampoules. The expiry date refers to the last date of that month. Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.

Do not store above 25°C and protect from light.

6. Contents of the pack and other information

What Physeptone Solution for Injection contains:

The active ingredient is Methadone Hydrochloride 25 mg / 1 ml. The other ingredient is water for injection.

What Physeptone Solution for Injection looks like and the content of the pack:

Physeptone Solution for Injection is a clear colourless solution supplied in clear glass ampoules, each containing 2ml of solution packed into a cardboard carton. Each pack contains 10 ampoules.

Marketing Authorisation Holder:

Macarthys Laboratories Ltd
T/A Martindale Pharma
Bampton Road
Harold Hill
United kingdom


Macarthys Laboratories Limited T/A Martindale Pharma
Bampton Road
Harold Hill

Product licenced number: PL 01883/0063

This leaflet was last revised in: August 2019