Relistor 8mg/0.4ml, Inj
It is used to treat constipation caused by some pain drugs.
Drug Class
Peripherally acting mu-opioid receptor antagonist (PAMORA)
Pharmacologic Class
Opioid antagonist
Pregnancy Category
Not available
FDA Approved
Apr 2008
DEA Schedule
Not Controlled
Overview
What is this medicine?
Relistor is an injection used to treat constipation caused by opioid pain medicines. It works by blocking the effects of opioids only in your gut, helping you have a bowel movement without affecting your pain relief.
How to Use This Medicine
Taking Your Medication Correctly
To ensure you get the most out of your medication, follow your doctor's instructions carefully. Read all the information provided with your medication and follow the instructions closely.
Administering the Injection
This medication is administered via injection into the fatty tissue under the skin, typically on the top of the thigh or in the belly area. If someone else is giving you the injection, it may be administered into the outer area of the upper arm. If you will be self-administering the injection, your doctor or nurse will provide guidance on the proper technique.
Before and after administering the injection, wash your hands thoroughly. Rotate the injection site with each dose to avoid irritation. Avoid injecting into skin that is irritated, tender, bruised, red, scaly, hard, scarred, or has stretch marks.
Inspecting the Medication
Check the solution for cloudiness, leakage, or particles before use. The medication should be colorless to faint yellow. Do not use the medication if the solution has changed color or appears abnormal in any way.
Using Prefilled Syringes or Vials
Each prefilled syringe or vial is for single use only. Discard any remaining medication after administering the dose. Dispose of needles and other sharp objects in a designated needle/sharp disposal box. Do not reuse needles or other items. When the disposal box is full, follow local regulations for proper disposal. If you have any questions, consult your doctor or pharmacist.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light and moisture. Do not store in a bathroom or freeze the medication. Keep all medications in a safe place, out of reach of children and pets.
Missed Doses
If you take your medication on a regular schedule and miss a dose, take it as soon as you remember. If it's close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses. If you take your medication as needed, do not take it more frequently than directed by your doctor.
To ensure you get the most out of your medication, follow your doctor's instructions carefully. Read all the information provided with your medication and follow the instructions closely.
Administering the Injection
This medication is administered via injection into the fatty tissue under the skin, typically on the top of the thigh or in the belly area. If someone else is giving you the injection, it may be administered into the outer area of the upper arm. If you will be self-administering the injection, your doctor or nurse will provide guidance on the proper technique.
Before and after administering the injection, wash your hands thoroughly. Rotate the injection site with each dose to avoid irritation. Avoid injecting into skin that is irritated, tender, bruised, red, scaly, hard, scarred, or has stretch marks.
Inspecting the Medication
Check the solution for cloudiness, leakage, or particles before use. The medication should be colorless to faint yellow. Do not use the medication if the solution has changed color or appears abnormal in any way.
Using Prefilled Syringes or Vials
Each prefilled syringe or vial is for single use only. Discard any remaining medication after administering the dose. Dispose of needles and other sharp objects in a designated needle/sharp disposal box. Do not reuse needles or other items. When the disposal box is full, follow local regulations for proper disposal. If you have any questions, consult your doctor or pharmacist.
Storing and Disposing of Your Medication
Store your medication at room temperature, protected from light and moisture. Do not store in a bathroom or freeze the medication. Keep all medications in a safe place, out of reach of children and pets.
Missed Doses
If you take your medication on a regular schedule and miss a dose, take it as soon as you remember. If it's close to the time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses. If you take your medication as needed, do not take it more frequently than directed by your doctor.
Lifestyle & Tips
- Continue to follow your doctor's instructions regarding your opioid pain medication.
- Maintain adequate hydration and fiber intake as advised by your healthcare provider.
- Do not take more Relistor than prescribed, as this may increase the risk of side effects.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
For Opioid-Induced Constipation (OIC) in advanced illness: 8 mg SC every other day for patients weighing 38-62 kg. For patients weighing 62-114 kg, the dose is 12 mg SC every other day. For OIC in chronic non-cancer pain: 12 mg SC once daily.
Dose Range:
8 - 12 mg
Condition-Specific Dosing:
advancedIllness:
8 mg SC every other day (for 38-62 kg) or 12 mg SC every other day (for 62-114 kg)
chronicNonCancerPain:
12 mg SC once daily
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No adjustment needed (CrCl 60-89 mL/min)
Moderate:
No adjustment needed (CrCl 30-59 mL/min)
Severe:
For OIC in advanced illness (CrCl < 30 mL/min): 8 mg SC every other day. For OIC in chronic non-cancer pain (CrCl < 30 mL/min): 8 mg SC once daily.
Dialysis:
Not studied in patients on dialysis. Use with caution and monitor for adverse effects.
Hepatic Impairment:
Mild:
No adjustment
Moderate:
No adjustment
Severe:
Not studied. Use with caution and monitor for adverse effects.
Pharmacology
Mechanism of Action
Methylnaltrexone is a selective, peripherally acting mu-opioid receptor antagonist. It blocks the binding of opioids to mu-opioid receptors in the gastrointestinal tract, thereby reversing opioid-induced constipation without affecting the analgesic effects of opioids on the central nervous system, as it does not readily cross the blood-brain barrier.
Pharmacokinetics
Absorption:
Bioavailability:
82% (subcutaneous)
Tmax:
0.5-1 hour (subcutaneous)
FoodEffect:
Not applicable for injection
Distribution:
Vd:
1.1 L/kg
ProteinBinding:
11-15%
CnssPenetration:
Limited
Elimination:
HalfLife:
8 hours
Clearance:
Not available
ExcretionRoute:
Primarily renal (60-70% unchanged), some fecal
Unchanged:
60-70%
Pharmacodynamics
OnsetOfAction:
Within 30-60 minutes (for bowel movement)
PeakEffect:
Not applicable (effect is a bowel movement)
DurationOfAction:
Up to 24 hours
Safety & Warnings
Side Effects
Serious Side Effects: Seek Medical Attention Immediately
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Chills
Shakiness
Abdominal swelling
Severe stomach pain or swelling that worsens or persists
Vomiting blood or material that resembles coffee grounds
Persistent upset stomach or vomiting
Black, tarry, or bloody stools
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or do not resolve, contact your doctor for guidance:
Stomach pain
Upset stomach or vomiting
Excessive sweating
Gas
Dizziness
Flushing
* Diarrhea (which can be severe; consult your doctor for advice on managing severe or prolonged diarrhea)
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Chills
Shakiness
Abdominal swelling
Severe stomach pain or swelling that worsens or persists
Vomiting blood or material that resembles coffee grounds
Persistent upset stomach or vomiting
Black, tarry, or bloody stools
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms that bother you or do not resolve, contact your doctor for guidance:
Stomach pain
Upset stomach or vomiting
Excessive sweating
Gas
Dizziness
Flushing
* Diarrhea (which can be severe; consult your doctor for advice on managing severe or prolonged diarrhea)
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe or persistent abdominal pain
- Nausea or vomiting
- Diarrhea
- Signs of opioid withdrawal (e.g., sweating, chills, abdominal cramping, diarrhea, anxiety, yawning)
- Allergic reaction (rash, itching, swelling, severe dizziness, trouble breathing)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the symptoms you experienced.
If you have a bowel blockage or are at risk for developing one.
If you are currently taking another medication similar to this one. If you are unsure, consult your doctor or pharmacist for clarification.
If you are breastfeeding. Note that you should not breastfeed while taking this medication.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine if it is safe to take this medication in conjunction with your other medications and health issues. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the symptoms you experienced.
If you have a bowel blockage or are at risk for developing one.
If you are currently taking another medication similar to this one. If you are unsure, consult your doctor or pharmacist for clarification.
If you are breastfeeding. Note that you should not breastfeed while taking this medication.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health conditions with your doctor and pharmacist. They will help determine if it is safe to take this medication in conjunction with your other medications and health issues. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. After using this drug, be prepared to have access to a bathroom, as most people experience a bowel movement within a few minutes to a few hours.
Before combining a laxative with this medication, consult your doctor to discuss potential interactions. This medication is specifically designed for patients who are taking opioid pain medications. If you stop taking your opioid pain medication, notify your doctor, as signs of opioid withdrawal may occur. Be aware of symptoms such as excessive sweating, chills, diarrhea, stomach pain, anxiety, irritability, or yawning, and contact your doctor immediately if you experience any of these.
The effectiveness of this medication may be reduced in individuals who have been taking opioid pain medications for less than 4 weeks. If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant or planning to become pregnant, consult your doctor to discuss the benefits and risks of using this medication during pregnancy. If this medication is used during pregnancy, it may cause withdrawal symptoms in the unborn baby, and your doctor will need to monitor the baby's health after the medication is administered.
Before combining a laxative with this medication, consult your doctor to discuss potential interactions. This medication is specifically designed for patients who are taking opioid pain medications. If you stop taking your opioid pain medication, notify your doctor, as signs of opioid withdrawal may occur. Be aware of symptoms such as excessive sweating, chills, diarrhea, stomach pain, anxiety, irritability, or yawning, and contact your doctor immediately if you experience any of these.
The effectiveness of this medication may be reduced in individuals who have been taking opioid pain medications for less than 4 weeks. If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant or planning to become pregnant, consult your doctor to discuss the benefits and risks of using this medication during pregnancy. If this medication is used during pregnancy, it may cause withdrawal symptoms in the unborn baby, and your doctor will need to monitor the baby's health after the medication is administered.
Overdose Information
Overdose Symptoms:
- Exacerbation of side effects (e.g., severe abdominal pain, diarrhea)
- Potential for opioid withdrawal symptoms if blood-brain barrier is compromised
What to Do:
Seek immediate medical attention or call 911. Contact a poison control center at 1-800-222-1222. Treatment is supportive.
Drug Interactions
Moderate Interactions
- Other opioid antagonists (e.g., naltrexone, naloxone) - theoretical risk of additive effects or opioid withdrawal.
Monitoring
Baseline Monitoring
Bowel function history
Rationale: To establish baseline constipation severity and frequency.
Timing: Prior to initiation of therapy
Renal function (CrCl)
Rationale: To determine appropriate dosing in patients with renal impairment.
Timing: Prior to initiation of therapy
Routine Monitoring
Bowel movement frequency and consistency
Frequency: Daily
Target: Regular, soft bowel movements
Action Threshold: Lack of response after 3 days, or worsening constipation
Abdominal pain/discomfort
Frequency: Daily
Target: Minimal to no pain
Action Threshold: Severe or worsening abdominal pain, especially with nausea/vomiting
Signs/symptoms of opioid withdrawal
Frequency: Daily, especially after first few doses
Target: Absence of withdrawal symptoms
Action Threshold: Diaphoresis, piloerection, abdominal cramping, diarrhea, anxiety, yawning
Symptom Monitoring
- Abdominal pain
- Nausea
- Diarrhea
- Flatulence
- Dizziness
- Symptoms of opioid withdrawal (e.g., sweating, chills, abdominal cramping, diarrhea, anxiety, yawning)
Special Patient Groups
Pregnancy
Limited human data on methylnaltrexone use in pregnant women are insufficient to inform a drug-associated risk for major birth defects and miscarriage. Animal studies show no adverse developmental effects. Use only if the potential benefit justifies the potential risk to the fetus.
Trimester-Specific Risks:
First Trimester:
Limited data, animal studies show no adverse effects.
Second Trimester:
Limited data, animal studies show no adverse effects.
Third Trimester:
Limited data, animal studies show no adverse effects.
Lactation
Methylnaltrexone is present in human milk. However, due to its low oral bioavailability, systemic exposure to the breastfed infant is expected to be low. Monitor breastfed infants for signs of gastrointestinal distress (e.g., diarrhea).
Infant Risk:
Low risk, monitor for GI effects.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Not recommended for use in pediatric patients.
Geriatric Use
No overall differences in safety or effectiveness were observed between elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. Dose adjustment based on age alone is not required, but consider age-related decline in renal function.
Clinical Information
Clinical Pearls
- Relistor is a peripherally acting mu-opioid receptor antagonist (PAMORA) and should not be confused with centrally acting opioid antagonists like naloxone or naltrexone.
- It is specifically for opioid-induced constipation and should not be used for other types of constipation.
- Patients should be advised to discontinue other laxatives when starting Relistor, then reintroduce them if needed, as directed by their healthcare provider.
- Administer subcutaneously in the thigh, abdomen, or upper arm. Rotate injection sites.
- Monitor for signs of opioid withdrawal, especially if the patient's blood-brain barrier is compromised (e.g., primary brain tumors, active CNS lesions, or conditions that disrupt the integrity of the blood-brain barrier).
- A bowel movement typically occurs within 30-60 minutes after injection.
Alternative Therapies
- Naloxegol (Movantik)
- Naldemedine (Symproic)
- Lubiprostone (Amitiza)
- Linaclotide (Linzess)
- Prucalopride (Motegrity)
- Traditional laxatives (e.g., polyethylene glycol, docusate sodium, senna)
Cost & Coverage
Average Cost:
Varies, typically $100-$200 per single-use pre-filled syringe
Insurance Coverage:
Tier 3 or Non-preferred Brand, may require prior authorization
General Drug Facts
If your symptoms or health problems do not improve or worsen over time, it is essential to contact your doctor for further evaluation and guidance. To ensure your safety and the effectiveness of your treatment, never share your medication with others or take someone else's medication.
This medication is accompanied by a Medication Guide, which is a valuable resource that provides important information about your treatment. It is crucial to read this guide carefully and review it again whenever your prescription is refilled. If you have any questions or concerns about your medication, do not hesitate to discuss them with your doctor, pharmacist, or other healthcare provider.
In the event of a suspected overdose, it is vital to seek immediate medical attention. Call your local poison control center or visit the emergency room right away. When seeking help, be prepared to provide detailed information about the overdose, including the name of the medication taken, the amount consumed, and the time it occurred. This information will help healthcare professionals provide you with the most effective treatment and care.
This medication is accompanied by a Medication Guide, which is a valuable resource that provides important information about your treatment. It is crucial to read this guide carefully and review it again whenever your prescription is refilled. If you have any questions or concerns about your medication, do not hesitate to discuss them with your doctor, pharmacist, or other healthcare provider.
In the event of a suspected overdose, it is vital to seek immediate medical attention. Call your local poison control center or visit the emergency room right away. When seeking help, be prepared to provide detailed information about the overdose, including the name of the medication taken, the amount consumed, and the time it occurred. This information will help healthcare professionals provide you with the most effective treatment and care.