Consumer medicine information

What is in this leaflet

This leaflet answers some common questions about Physeptone injection. It does not contain all of the available information.
It does not take the place of talking to your doctor.
All medicines have risks and benefits. Your doctor has weighed the risks of giving you Physeptone injection against the benefits they expect it will have for you.
If you have any concerns about being given this medicine, ask your doctor.
Keep this leaflet while being treated.
You may need to read it again.

What is Physeptone injection used for

Physeptone injection contains methadone hydrochloride as the active ingredient, which belongs to a group of medicines called opioid analgesics.
Physeptone injection is used for the relief of moderate to severe pain.
Addiction
You can become addicted to Physeptone even if you are given it exactly as prescribed. Physeptone may become habit forming causing mental and physical dependence. If abused, it may become less able to reduce pain.
Dependence
As with all other opioid containing products, your body may become used to you being given this medicine. Using it may result in physical dependence. Physical dependence means that you may experience withdrawal symptoms if you stop using Physeptone suddenly, so it is important to take it exactly as directed by your doctor.
Tolerance
Tolerance to Physeptone may develop, which means that the effect of the medicine may decrease. If this happens, more may be needed to maintain the same effect.
Withdrawal
Continue using your medicine for as long as your doctor tells you.
If you stop using this medicine suddenly, your pain may worsen and you may experience some or all of the following withdrawal symptoms:

• nervousness, restlessness, agitation, trouble sleeping or anxiety

• body aches, weakness or stomach cramps

• loss of appetite, nausea, vomiting or diarrhoea

• increased heart rate, breathing rate or pupil size

• watery eyes, runny nose, chills or yawning

• increased sweating.

Before you are given it

When you must not be given it:

• you have ever had an allergic reaction to methadone hydrochloride or any other opioid drug

• you have any other medical condition including:
  - suffering from a lung disorder such as asthma, or any illness causing difficulty in breathing, especially if there is excessive phlegm or skin is bluish in colour
  - a recent head injury, or increased pressure in the head
  - a bowel condition known as ulcerative colitis
  - certain liver or kidney conditions
  - certain heart conditions
  - alcoholism.

• you are taking or have recently taken antidepressants of the type called monoamine oxidase inhibitors (MAOIs)

• you suffer from biliary and renal tract spasm.

Before you are given it

• you are allergic to foods, dyes, preservatives or any other medicines

• you are pregnant, or become pregnant while taking Physeptone Injection, are about to give birth, or are breastfeeding

• you have any other medical condition including:
  - hormone problems
  - diabetes
  - prostate disease
  - phaeochromocytoma (a rare tumour of the adrenal gland). Symptoms include bouts of anxiety and headaches. There may be palpitations (banging of the heart felt in the chest), dizziness, weakness, nausea, vomiting, diarrhoea, dilated pupils, blurry vision, stomach pains and raised blood pressure.

Taking other medicines

How it is given

Physeptone Injection will be administered under the supervision of a doctor.
It is administered by injection into a muscle or just under the skin.
Your doctor will explain to you how long your course of treatment with Physeptone injection will be and will advise you when the treatment is complete.

Use in children and elderly patients

If you are given too much (overdose)

• slow, unusual or difficult breathing

• drowsiness, dizziness or unconsciousness

• slow or weak heartbeat

• nausea or vomiting

• convulsions or fits.

• phone the Poisons Information Centre (by calling 13 11 26), or

• contact your doctor, or

• go to the Emergency Department at your nearest hospital.

While you are having it

Things to be careful of

Side effects

Tell your doctor as soon as possible if you do not feel well while you are being given Physeptone injection.
All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical treatment if you get some of the side effects.
Ask your doctor or pharmacist to answer any questions you may have.
With prolonged use, the dose may have to be increased to achieve the same benefit, whilst a sudden decrease in dose or interruption of therapy may give rise to withdrawal symptoms.
Tell your doctor if you notice any of the following and they worry you.


Tell your doctor if you notice anything else that is making you feel unwell, even if you think the problems are not connected with this medicine and are not referred to in this leaflet.
Other side effects not listed above may also occur in some people.
Do not be alarmed by this of possible side effects.
You may not experience any of them.

After using it

Storage

Product description

What it looks like

Ingredients

Sponsor

Aspen Pharmacare Australia Pty Ltd
34-36 Chandos Street
St Leonards NSW 2065
Australia
Australian Registration Number:
AUST R 159750
This leaflet was revised in December 2024.

Boxed Warnings

Limitations of use. Because of the risks associated with the use of opioids, Physeptone should only be used in patients for whom other treatment options, including non-opioid analgesics, are ineffective, not tolerated or otherwise inadequate to provide appropriate management of pain (see Section 4.4 Special Warnings and Precautions for Use).
Hazardous and harmful use. Physeptone poses risks of hazardous and harmful use which can lead to overdose and death. Assess the patient's risk of hazardous and harmful use before prescribing and monitor the patient regularly during treatment (see Section 4.4 Special Warnings and Precautions for Use).
Life threatening respiratory depression. Serious, life-threatening or fatal respiratory depression may occur with the use of Physeptone. Be aware of situations which increase the risk of respiratory depression, modify dosing in patients at risk and monitor patients closely, especially on initiation or following a dose increase (see Section 4.4 Special Warnings and Precautions for Use).
Concomitant use of benzodiazepines and other central nervous system (CNS) depressants, including alcohol. Concomitant use of opioids with benzodiazepines, gabapentinoids, antihistamines, tricyclic antidepressants, antipsychotics, cannabis or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Limit dosages and durations to the minimum required; and monitor patients for signs and symptoms of respiratory depression and sedation. Caution patients not to drink alcohol while taking Physeptone.

1 Name of Medicine

Methadone hydrochloride.

2 Qualitative and Quantitative Composition

Methadone hydrochloride is a synthetic opioid analgesic with the general properties of morphine.
Physeptone tablets contain methadone hydrochloride 10 mg.
List of excipients with known effect. Lactose monohydrate.
Physeptone injection vials contain methadone hydrochloride 10 mg/1 mL (preservative free).
For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

Physeptone tablets. White, biconvex scored tablet on one side and plain on the other.
Physeptone injection. A clear, colourless solution free of particulate matter.

4 Clinical Particulars

4.9 Overdose

Symptoms. Toxic doses of methadone cause unconsciousness, pin-point pupils, slow shallow respiration, cyanosis and weak pulse, profound respiratory depression, hypotension, circulatory failure and pulmonary oedema, coma and death. Mydriasis may replace miosis as asphyxia intervenes. Drowsiness, floppiness, pin-point pupils and apnoea have been reported in children. Often there is a 2-3 hour delay between ingestion and the appearance of symptoms. Hypoglycaemia has been reported. These symptoms and signs of overdosage parallel those for other opioids.
Treatment. General supportive measures, including ECG monitoring, should be employed as required. Lavage, dialysis and CNS stimulation are contraindicated. The specific opioid antagonist naloxone is the treatment of choice for the reversal of coma and the restoration of spontaneous respiration. Intravenous naloxone should be given and repeated at 5-10 minute intervals to attain full benefit. Intravenous infusion is the preferred route of administration in the management of methadone overdose. Because of the short half-life of naloxone relative to the long half-life of methadone, continuous infusion reduces the possibility of prolonged respiratory depression and the risk of relapse, which can occur suddenly. It should be noted that QT prolongation will not be reversed by naloxone.
In opioid dependent patients the administration of the usual dose of an opioid antagonist will precipitate an acute withdrawal syndrome. The severity of this syndrome will depend on the degree of physical dependence and the dose of the antagonist administered. The use of an opioid antagonist in such a person should be avoided if possible. If it must be used to treat serious respiratory depression in the physically dependent person the antagonist should be administered with extreme care and by titration with smaller than usual doses of the antagonist.
Acidification of the urine will increase the rate of elimination of the drug via the kidney.
Patients should be monitored closely for at least 48 hours after apparent recovery in case of relapse, since the duration of action of the antagonist may be substantially shorter than that of methadone.
The use of other respiratory or central stimulants is not recommended.
Methadone is not dialysable by either peritoneal or haemodialysis.
For information on the management of overdose, contact the Poisons Information Centre for advice on 13 11 26 (Australia).

5 Pharmacological Properties

5.3 Preclinical Safety Data

Mutagenic potential. Methadone did not exhibit demonstrable mutagenic activity in a wide range of standard in vitro and in vivo mutagenicity assays. However, in a Dominant Lethal assay in mice, treatment with methadone at doses between 1 and 6 mg/kg was associated with increased pre-implantation deaths and chromosomal aberrations of sperm cells when compared with controls.
Genotoxicity/carcinogenicity. Long term carcinogenicity tests in rodents did not reveal any evidence of methadone-related neoplasia.
Teratogenic potential. No teratogenic effects have been observed in standard teratogenicity studies in rats and rabbits given methadone at doses from ten to fifty times the average daily human maintenance dose. Developmental abnormalities of the central nervous system have been reported in hamsters and mice given high doses in early pregnancy.

6 Pharmaceutical Particulars

6.7 Physicochemical Properties

Methadone is a racemic mixture and levo-methadone is the active isomer. Methadone occurs as odourless, colourless crystals or white crystalline powder. It is soluble in water, freely soluble in alcohol and chloroform; practically insoluble in ether and in glycerol.
The chemical name for methadone hydrochloride is 6-Dimethylamino-4,4-diphenyl-3-heptanone hydrochloride. Molecular formula: C₂₁H₂₇NO,HCl. Relative molecular mass: 345.9.
Chemical structure.
https://stagingapi.mims.com/au/public/v2/images/fullchemgif/CSMETHYD.gif CAS number. 61849-14-7.

7 Medicine Schedule (Poisons Standard)

S8 - Controlled Drug.

Summary Table of Changes

https://stagingapi.mims.com/au/public/v2/images/fulltablegif/PHYSEPST.gif