PMS-Methadone: Uses, Side Effects and Dosage

Serious warnings and precautions box

What pms-METHADONE is used for:

pms-METHADONE is used in adults for the long-term management of pain, when:

• The pain is severe enough to require daily, around-the-clock painkillers;
• The healthcare professional determines that other treatment options are not able to effectively treat your pain.

pms-METHADONE is NOT used “as needed” to treat pain that you only have once in a while.

How pms-METHADONE works:

pms-METHADONE is a painkiller belonging to the class of medicines known as opioids. It relieves pain by acting on specific nerve cells of the spinal cord and brain.

The ingredients in pms-METHADONE are:

Medicinal ingredient: methadone hydrochloride

Non-medicinal ingredients: lactose, magnesium stearate and microcrystalline cellulose.

The following tablet strengths also contain:

• 1 mg: FD&C Blue No. 1
• 5 mg: FD&C Yellow No. 6
• 10 mg: FD&C Yellow No. 10 Aluminum, FD&C Blue No. 1

pms-METHADONE comes in the following dosage form:

Tablets: 1 mg, 5 mg, 10 mg and 25 mg.

Do not use pms-METHADONE if:

• your healthcare professional did not prescribe it for you.
• you are allergic to methadone hydrochloride, other opioids or any of the other ingredients in pms-METHADONE.
• you have never taken an opioid before.
• you can control your pain by the occasional use of other pain medications. This includes those available without a prescription.
• you have severe asthma, trouble breathing, or cor pulmonale (a heart problem related to lung issues).
• you have any heart problems.
• you have bowel blockage or narrowing of the stomach or intestines.
• you have a condition where the bowel does not work properly (ileus) or have severe pain in your abdomen.
• you have severe diarrhea caused by antibiotics or food poisoning.
• you have a head injury or other risks for seizure.

• you suffer from alcoholism or alcohol withdrawal.

• you are going to have a surgery or operation, or have had a surgery within the last 24 hours.
• you are taking or, have taken within the past 14 days, a certain type of antidepressant called Monoamine Oxidase Inhibitors (MAOIs)
• you are pregnant or planning to become pregnant, or you are in labour or delivery.
• you are breastfeeding.
• you have rare inherited diseases which affect how your body uses sugar lactose. pms-METHADONE tablets contain lactose.

To help avoid side effects and ensure proper use, talk to your healthcare professional before you take pms-METHADONE. Talk about any health conditions or problems you may have, including if you:

• have a history of illicit drugs or prescription drug or alcohol abuse.
• are taking any other medications.
• are drinking or planning to drink alcohol or take medications that contain alcohol.
• have, or are at risk for, heart disease or heart rhythm problems. Ask your healthcare professional if you are not sure.
• have low blood pressure.
• have kidney or liver problems.
• have problems with your thyroid, adrenal or prostate gland.
• have epilepsy or a history of seizures (convulsions).
• are over 65 years of age.
• have a sleep disorder which causes pauses in breathing or shallow breathing while sleeping (sleep apnea).
• have, or have a history of, problems with your mood (such as depression or anxiety), or other mental health problems.
• have difficulty urinating.
• suffer from chronic or severe constipation.
• suffer from migraines.
• are lactose intolerant.

Other warnings you should know about:

Opioid dependence and addiction: Like any opioid, pms-METHADONE may cause mental and physical dependence; it also has the potential to cause addiction. There are important differences between physical dependence and addiction. If you use opioids for a long time, you may develop tolerance. This means that you may need higher doses of pms-METHADONE to feel the same level of pain relief. It is important that you talk to your healthcare professional if you have questions or concerns about addiction, physical dependence, or tolerance. Your healthcare professional should prescribe and administer pms-METHADONE with the same degree of caution appropriate to the use of other oral opioid medications. It is not recommended to use these products for a long period of time.

Pregnancy, nursing, labour and delivery: Do not use pms-METHADONE while pregnant, nursing, during labour or delivery. Opioids can be transferred to your baby through breast milk, or while still in the womb. pms-METHADONE can then cause life-threatening breathing problems in your unborn baby or nursing infant.

If you are pregnant and are taking pms-METHADONE, it is important that you don’t stop taking your medication all of a sudden. If you do, it can cause a miscarriage or a still-birth. Your healthcare professional will monitor and guide you on how to slowly stop taking pms-METHADONE. This may help avoid serious harm to your unborn baby.

Driving and using machines: Before you do tasks which may require special attention, you should wait until you know how you react to pms-METHADONE. pms-METHADONE can cause:

• drowsiness;
• dizziness; or
• light headedness.

This can usually occur after you take your first dose and when your dose is increased.

Disorder of the adrenal gland: You may develop a disorder of the adrenal gland called adrenal insufficiency. This means that your adrenal gland is not making enough of certain hormones. You may experience symptoms such as:

• nausea, vomiting;
• feeling tired, weak or dizzy;
• decreased appetite.

You may be more likely to have problems with your adrenal gland if you have been taking opioids for longer than one month. Your healthcare professional may do tests, give you another medication, and slowly take you off pms-METHADONE.

Serotonin toxicity (also known as serotonin syndrome): pms-METHADONE can cause serotonin toxicity, a rare but potentially life-threatening condition. It can cause serious changes in how your brain, muscles and digestive system work. You may develop serotonin toxicity if you take pms-METHADONE with certain anti-depressants or migraine medications.

Serotonin toxicity symptoms include:

• fever, sweating, shivering, diarrhea, nausea, vomiting;
• muscle shakes, jerks, twitches or stiffness, overactive reflexes, loss of coordination;
• fast heartbeat, changes in blood pressure;
• confusion, agitation, restlessness, hallucinations, mood changes, unconsciousness, and coma.

Sexual Function/Reproduction: Long term use of opioids may lead to a decrease in sex hormone levels. It may also lead to low libido (desire to have sex), erectile dysfunction or being infertile.

Sleep Apnea: Opioids can cause a problem called sleep apnea (stopping breathing from time to time while sleeping). Tell your healthcare professional if you have a history of sleep apnea or if anyone notices that you stop breathing from time to time while sleeping.

Worsening pain: Taking opioids for pain can sometimes have the unintended effect of making your pain feel worse (opioid-induced hyperalgesia) even though your opioid dose has been unchanged or increased. This can also include feeling pain in new places in your body, or feeling pain from something that would not normally hurt, for example, feeling pain from clothing touching your skin. Tell your healthcare professional if you notice a change like this in your pain while you are taking pms-METHADONE.

Gastrointestinal disorders: Taking opioids for a long time can cause problems with your throat that can affect swallowing. This usually happens within weeks to months after starting treatment with an opioid medication. Common symptoms include difficulty swallowing, heartburn, and chest pain. Serious gastrointestinal problems can also occur such as muscle spasms or obstruction of the esophagus.

Testing and check-ups: Your healthcare professional will regularly monitor your health. This includes monitoring for signs of:

• misuse and abuse;
• sleep apnea (a sleep disorder which causes pauses in breathing or shallow breathing while sleeping);
• respiratory depression and sedation (e.g., slow, shallow, or weak breathing);
• low blood pressure;
• problems with your heart rhythm.

Tell your healthcare professional about all the medicines you take, including any drugs, vitamins, minerals, natural supplements or alternative medicines.

Serious drug interactions

The following may also interact with pms-METHADONE:

• anticonvulsants used to treat seizures (e.g., phenytoin, carbamazepine, phenobarbital);
• anticoagulants used to thin the blood and prevent blood clots (e.g., warfarin and other coumarins);
• antiretrovirals used to treat viral infections (e.g., nevirapine, efavirenz, ritonavir, lopinavir, zidovudine, didanosine, stavudine);
• antifungals used to treat fungal infections (e.g., ketoconazole, voriconazole);
• antibiotics used to treat bacterial infections (e.g., erythromycin, rifampin);
• medicines used to treat migraines (e.g., triptans);
• antiarrhythmics used to treat an abnormal heart rhythm;
• calcium channel blockers used to lower blood pressure;
• medicines used to regulate salt and water balances in the body (e.g., diuretics, mineralocorticoid hormones, laxatives).

How to take pms-METHADONE:

• Take pms-METHADONE exactly as your healthcare professional tells you to. Do NOT increase, decrease, or stop taking your dose without talking to your healthcare professional.
• pms-METHADONE must be taken orally, by mouth. Do NOT take pms-METHADONE any other way.
• Swallow pms-METHADONE tablets whole. Do not break, chew, dissolve or crush.
• Do not use pms-METHADONE for injection or rectal administration

Usual dose:

Your dose is tailored/personalized just for you. Your healthcare professional will prescribe you the lowest dose that works to control your pain. During treatment, your healthcare professional may adjust your dose based on the severity of your pain and your response to the treatment. Follow their instructions closely.

Review your pain regularly with your healthcare professional to determine if you still need pms-METHADONE. Be sure to take pms-METHADONE only for the condition for which it was prescribed.

If your pain increases or you develop any side effects as a result of taking pms-METHADONE, tell your healthcare professional immediately.

Stopping your Medication:

If you have been taking pms-METHADONE for more than a few days, you should not stop taking it all of a sudden.

Your healthcare professional will monitor and guide you on how to slowly stop taking pms-METHADONE. You should do it slowly to avoid uncomfortable symptoms such as having:

• body aches;
• diarrhea;
• goosebumps;
• loss of appetite;
• nausea;
• feeling nervous or restless;
• runny nose;
• sneezing;
• tremors or shivering;
• stomach cramps;
• rapid heart rate (tachycardia);
• having trouble with sleeping;
• an unusual increase in sweating;
• heart palpitations;
• an unexplained fever;
• weakness;
• vomiting;
• yawning.

By reducing or stopping your opioid treatment, your body will become less used to opioids. If you start treatment again, you will need to start at the lowest dose. You may overdose if you restart at the last dose you took before you slowly stopped taking pms-METHADONE.

Refilling your prescription for pms-METHADONE:

A new written prescription is required from your healthcare professional each time you need more pms-METHADONE. Therefore, it is important that you contact your healthcare professional before your current supply runs out.

Only obtain prescriptions for this medicine from the healthcare professional in charge of your treatment. Do not seek prescriptions from other healthcare professionals unless you switch to another healthcare professional for your pain management.

Overdose:

Signs of overdose with pms-METHADONE may include:

• unusually slow or weak breathing;
• dizziness;
• confusion;
• extreme drowsiness;
• muscle weakness;
• cold and clammy skin;
• slow heart rate;
• shrinking or widening of pupils.

Missed dose:

It is important that you do not miss any doses. However, if you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, then skip the missed dose. Do not take two doses at once. If you miss several doses in a row, talk to your healthcare professional before restarting your medication.

Possible side effects from using pms-METHADONE:

These are not all the possible side effects you may have when taking pms-METHADONE. If you experience any side effects not listed here, tell your healthcare professional.

Side effects with pms-METHADONE may include:

• Drowsiness
• Insomnia
• Dizziness
• Fainting
• Lightheadedness
• Nausea, vomiting, poor appetite
• Dry mouth
• Headache
• Problems with vision
• Weakness, uncoordinated muscle movement
• Itching
• Sweating, facial flushing
• Constipation. Talk with your healthcare professional about ways to prevent constipation when you start using pms-METHADONE.
• Low sex drive, impotence (erectile dysfunction), infertility

Serious side effects and what to do about them

If you have a troublesome symptom or side effect that is not listed here or becomes bad enough to interfere with your daily activities, tell your healthcare professional.

Reporting side effects

Storage:

• Store at room temperature (15°- 30°C) in tight container, protected from light.
• Keep unused or expired pms-METHADONE in a secure place to prevent theft, misuse or accidental exposure. It should be kept under lock, out of sight and reach of children and pets.
• Never take medicine in front of small children as they will want to copy you. Accidental ingestion by a child is dangerous and may result in death. If a child accidentally takes pms-METHADONE, get emergency help right away.
• pms-METHADONE should never be thrown into household trash, where children and pets may find it. It should be returned to a pharmacy for proper disposal.

If you want more information about pms-METHADONE:

• Talk to your healthcare professional.
• Find the full product monograph that is prepared for healthcare professionals and includes the Patient Medication Information by visiting the Health Canada Drug Product Database website: (https://www.canada.ca/en/health-canada/services/drugs-health-products/drug-products/drug-product-database.html); the distributor’s website www.paladin-pharma.com; or by calling 1-888-867-7426.

Date of Authorization: 2025-05-16