Methylene Blue 1% Inj, 1ml

Methylene blue acts as a redox agent. In methemoglobinemia, it is reduced by NADPH-dependent methemoglobin reductase to leucomethylene blue. Leucomethylene blue then reduces the ferric iron (Fe3+) in methemoglobin to the ferrous iron (Fe2+) in hemoglobin, restoring oxygen-carrying capacity. Methylene blue itself is then re-oxidized to methylene blue, completing the cycle. It also has oxidase activity and can inhibit nitric oxide synthase and guanylate cyclase, contributing to its off-label uses (e.g., vasoplegic shock).

Urgent Side Effects: Seek Medical Help Right Away

While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:

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
Signs of electrolyte problems, including:
+ Mood changes
+ Confusion
+ Muscle pain, cramps, or spasms
+ Weakness
+ Shakiness
+ Change in balance
+ Abnormal heartbeat
+ Seizures
+ Loss of appetite
+ Severe upset stomach or vomiting
Dizziness or fainting
Confusion
Changes in vision
Feeling extremely tired or weak
Pale skin
Dark urine or yellowing of the skin or eyes
Seizures

Other Possible Side Effects

Like all medications, this drug can cause side effects. Although many people do not experience any side effects or only have mild ones, it is essential to discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms, contact your doctor for advice:

Urine or stool turning blue or green (this is a normal and harmless effect)
Skin turning blue-green
Pain, redness, or swelling at the injection site
Diarrhea or stomach upset
Headache

Reporting Side Effects

This list is not exhaustive, and you may experience other side effects. If you have questions or concerns, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

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 allergic reaction you experienced, including the symptoms that occurred.
If you have a condition called G6PD deficiency.
If you are pregnant or think you might be pregnant. This medication may pose a risk to your unborn baby, so it is crucial to discuss the potential benefits and risks with your doctor to determine if this medication is suitable for you.
If you are breastfeeding. You should not breastfeed while taking this medication or for 8 days after your last dose.

Additionally, this medication may interact with other medications or health conditions. Therefore, it is vital to provide your doctor and pharmacist with a comprehensive list of:

All prescription and over-the-counter medications you are taking
Any natural products or vitamins you are using
* Your medical history, including any health problems you have

Your doctor will help you determine if it is safe to take this medication with your other medications and health conditions. Do not start, stop, or change the dose of any medication without first consulting your doctor.

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular monitoring is crucial, so be sure to undergo blood work, other laboratory tests, blood pressure checks, and heart rate assessments as directed by your doctor. Additionally, you will need to have your heart rhythm checked with an electrocardiogram (ECG) as scheduled.

Please note that this medication may interfere with certain laboratory tests. Therefore, it is vital to disclose that you are taking this drug to all your healthcare providers and laboratory personnel.

To ensure your safety, avoid operating a vehicle or engaging in activities that require alertness until you are aware of how this medication affects you. You may be more susceptible to sunburn, so it is recommended to limit your exposure to the sun, sunlamps, and tanning beds. When going outside, protect yourself from the sun by using sunscreen and wearing protective clothing and eyewear.

• Serotonergic drugs (SSRIs, SNRIs, MAOIs, TCAs, triptans, etc.) - risk of serotonin syndrome
• G6PD deficiency (risk of hemolytic anemia)
• Patients with known hypersensitivity to methylene blue or any component
• Patients with severe renal insufficiency (for diagnostic use)

• Drugs that prolong QT interval (theoretical risk, monitor ECG)
• Other oxidizing agents (may worsen methemoglobinemia)
• Drugs metabolized by CYP2D6 (methylene blue is a potent CYP2D6 inhibitor)

• Drugs metabolized by CYP1A2, CYP2C19, CYP3A4 (methylene blue is a moderate inhibitor)
• Anticoagulants (may affect coagulation tests, theoretical increased bleeding risk)
• Vasopressors (for vasoplegic shock, may have additive effects)

• None specifically identified as minor, most interactions are significant due to its enzyme inhibition and redox properties.

• Cyanosis (especially of lips, nail beds)
• Dyspnea, tachypnea
• Headache, dizziness, confusion
• Nausea, vomiting, abdominal pain
• Chest pain
• Arrhythmias
• Signs of serotonin syndrome (agitation, hyperthermia, rigidity, hyperreflexia, clonus, diaphoresis)
• Signs of hemolytic anemia (fatigue, pallor, jaundice, dark urine)

Use for methemoglobinemia only if clearly needed and benefits outweigh risks (Category C). For diagnostic use (e.g., amniocentesis), it is contraindicated (Category X) due to potential for fetal harm (e.g., hemolytic anemia, intestinal atresia).

Methylene blue is excreted into breast milk and can cause hemolytic anemia in G6PD deficient infants. It is generally recommended to avoid breastfeeding for up to 5 days after administration or to use an alternative drug. If breastfeeding cannot be interrupted, monitor the infant for signs of hemolysis.

Dosing is weight-based. Neonates and infants are more susceptible to hemolytic anemia, especially if G6PD deficient. Lower doses are recommended for neonates. Close monitoring for methemoglobin levels and signs of hemolysis is crucial.

No specific dose adjustments are generally required based solely on age, but elderly patients may have reduced renal or hepatic function, requiring cautious dosing and close monitoring. They may also be more susceptible to CNS side effects.

• Always check G6PD status before administering methylene blue for methemoglobinemia, if time permits. If G6PD deficiency is suspected or confirmed, methylene blue is contraindicated, and alternative treatments (e.g., exchange transfusion, hyperbaric oxygen) should be considered.
• Methylene blue can cause a false low reading on pulse oximetry due to its blue color interfering with light absorption. Arterial blood gas (ABG) with co-oximetry is essential for accurate methemoglobin level measurement and oxygen saturation.
• The maximum cumulative dose of 7 mg/kg should not be exceeded, as higher doses can paradoxically worsen methemoglobinemia or cause hemolytic anemia.
• Be vigilant for signs of serotonin syndrome, especially if the patient is on serotonergic medications. Methylene blue is a potent MAO-A inhibitor.
• Urine will turn blue-green; inform patients to prevent alarm.
• For diagnostic uses, ensure the correct concentration and route of administration to avoid systemic effects.

• Exchange transfusion (for severe methemoglobinemia, especially in G6PD deficiency or methylene blue failure)
• Hyperbaric oxygen (adjunctive therapy for severe methemoglobinemia or when methylene blue is contraindicated)
• Ascorbic acid (Vitamin C) (less effective, slower acting, for chronic or mild methemoglobinemia)
• For diagnostic uses, other dyes or imaging techniques may be alternatives depending on the specific procedure (e.g., indocyanine green, isosulfan blue, technetium-99m sulfur colloid).

If your symptoms or health problems persist or worsen, it is essential to contact your doctor promptly. To ensure safe use, never share your medication with others, and do not take medication prescribed for someone else. Store all medications in a secure location, out of the reach of children and pets, to prevent accidental ingestion. Dispose of unused or expired medications properly. Unless instructed to do so by a healthcare professional, do not flush medications down the toilet or pour them down the drain. If you are unsure about the proper disposal method, consult your pharmacist for guidance. Many communities have drug take-back programs, which your pharmacist can help you locate. Some medications may come with an additional patient information leaflet; check with your pharmacist to see if this applies to your prescription. If you have any questions or concerns about your medication, discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. Be prepared to provide information about the medication taken, the amount, and the time it was taken to ensure prompt and effective treatment.