💉 Methylthioninium Chloride Injection 10 mg/mL
(Also known as Methylene Blue)
🔹 Generic Name:
Methylthioninium chloride
🔹 Dosage Form & Strength:
- Injection: 10 mg/mL
- Commonly available in 1 mL, 5 mL, or 10 mL ampoules
📌 Primary Indications:
| Condition | Purpose |
|---|---|
| Methemoglobinemia (acquired or drug-induced) | Converts methemoglobin to hemoglobin |
| Ifosfamide-induced encephalopathy | Reduces neurotoxicity |
| Vasoplegic shock (off-label use) | Acts as a nitric oxide scavenger |
| Intraoperative tissue dye (e.g., fistula tract identification) | Diagnostic staining agent |
💡 Mechanism of Action:
Methylene blue functions as a reducing agent, converting methemoglobin (Fe³⁺) back to functional hemoglobin (Fe²⁺) via the NADPH methemoglobin reductase pathway.
It also inhibits nitric oxide synthase and guanylate cyclase, useful in vasoplegic states.
⚠️ Precautions & Warnings:
| Risk | Details |
|---|---|
| Serotonin Syndrome | Especially in patients on SSRIs/SNRIs/MAOIs |
| G6PD Deficiency | Risk of severe hemolysis — contraindicated |
| Blue discoloration | Urine, feces, and skin may turn blue-green |
| Phototoxicity | Use with caution in neonates and under light therapy |
🧴 Storage:
| Condition | Details |
|---|---|
| Storage | Store below 25°C; protect from light |
| Shelf life | Refer to manufacturer’s instructions |
| Appearance | Clear, dark blue solution |