PROVAYBLUE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PROVAYBLUE (PROVAYBLUE).
Methylthioninium chloride (methylene blue) acts by reducing methemoglobin to hemoglobin via the enzyme NADPH methemoglobin reductase, thereby restoring oxygen-carrying capacity of the blood.
| Metabolism | Primarily reduced to leukomethylene blue by NADPH-dependent reductases in erythrocytes and extravascular tissues; leukomethylene blue is then conjugated in liver to glucuronide and sulfate metabolites; excreted in urine and bile. |
| Excretion | Primarily renal excretion as unchanged drug. Approximately 45-60% of a dose is excreted unchanged in urine. Minor fecal elimination accounts for less than 10%. |
| Half-life | Terminal elimination half-life is approximately 10-15 hours. In patients with renal impairment, half-life may be prolonged; no dose adjustment recommended for mild-to-moderate impairment, but use caution in severe impairment. |
| Protein binding | Approximately 85-90% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 0.5-0.8 L/kg, indicating distribution into total body water. Higher Vd observed in patients with hypoalbuminemia. |
| Bioavailability | Not applicable; administered only intravenously. Bioavailability is 100% by IV route. |
| Onset of Action | Intravenous administration: Onset of clinical effect (reversal of methemoglobinemia) occurs within 30 minutes to 1 hour, with peak effect at 1-2 hours. |
| Duration of Action | Duration of effect is approximately 6-12 hours, corresponding to the time required for methemoglobin levels to return to normal. Clinical effects may persist longer in cases of severe methemoglobinemia or re-exposure. |
1-2 mg/kg intravenously over 5 minutes, may repeat once if needed. Maximum single dose: 300 mg.
| Dosage form | SOLUTION |
| Renal impairment | No specific dose adjustment required for renal impairment. Use with caution in severe renal impairment (eGFR <30 mL/min) due to potential accumulation. |
| Liver impairment | Mild to moderate hepatic impairment (Child-Pugh A or B): No adjustment. Severe hepatic impairment (Child-Pugh C): Use with caution; specific dose recommendations not established. |
| Pediatric use | Safety and efficacy not established in pediatric patients; use not recommended. |
| Geriatric use | No specific dose adjustment; start at lower end of dosing range due to potential age-related decreased organ function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PROVAYBLUE (PROVAYBLUE).
| Breastfeeding | Methylene blue is excreted in human breast milk. The milk-to-plasma (M/P) ratio is unknown. Based on limited data, the relative infant dose is estimated to be low, but there is potential for adverse effects such as methemoglobinemia, hemolysis (especially in G6PD-deficient infants), and photosensitivity. Breastfeeding should be avoided during treatment and for at least 48-72 hours after the last dose. |
| Teratogenic Risk | PROVAYBLUE (methylene blue) is a category C drug. There are no adequate and well-controlled studies in pregnant women. In animal studies, methylene blue has been shown to be teratogenic and embryotoxic when administered at high doses. First trimester exposure may be associated with hemolytic anemia and hyperbilirubinemia in neonates. Second and third trimester use may cause fetal distress, methemoglobinemia, and photosensitivity. Avoid use during pregnancy unless potential benefit justifies risk to fetus. |
■ FDA Black Box Warning
WARNING: SEROTONIN SYNDROME WHEN USED WITH SEROTONERGIC DRUGS. Methylene blue is a potent inhibitor of monoamine oxidase A (MAO-A). Concomitant use with serotonergic drugs such as SSRIs, SNRIs, MAOIs, and others may cause life-threatening serotonin syndrome.
| Serious Effects |
Hypersensitivity to methylene blue; severe renal impairment; patients with G6PD deficiency (risk of hemolytic anemia).
| Precautions | Risk of serotonin syndrome with concomitant serotonergic drugs; hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency; interference with pulse oximetry readings; hypersensitivity reactions; drug-induced methemoglobinemia at high doses (paradoxical); use in pregnancy only if clearly needed. |
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| Fetal Monitoring | Monitor maternal vital signs (blood pressure, heart rate, oxygen saturation), methemoglobin levels (especially if high doses used), and signs of serotonin syndrome if used with serotonergic drugs. Fetal monitoring includes heart rate assessment during labor and delivery. Neonatal assessment for hemolysis, hyperbilirubinemia, and methemoglobinemia is recommended. |
| Fertility Effects | Limited reproductive toxicity data. No specific human studies on fertility. Animal studies have shown no significant effects on fertility at therapeutic doses, but high doses may cause ovarian toxicity. Theoretical risk of oxidative stress affecting gametes. |