ORAQIX

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ORAQIX (ORAQIX).

How it works

Oraqix is a eutectic mixture of lidocaine and prilocaine that acts as a local anesthetic. It reversibly blocks sodium ion channels in nerve cell membranes, inhibiting the initiation and conduction of nerve impulses, thereby producing anesthesia.

What the body does with it

Metabolism	Lidocaine is primarily metabolized in the liver by cytochrome P450 enzymes, mainly CYP1A2 and CYP3A4, to metabolites including monoethylglycinexylidide (MEGX) and glycinexylidide (GX). Prilocaine is metabolized in the liver and kidneys to o-toluidine, which can cause methemoglobinemia. Both are excreted renally.
Excretion	Renal: ~60% unchanged; biliary/fecal: ~30% as metabolites and parent drug; total clearance approximates renal clearance.
Half-life	Terminal elimination half-life: 7.5 hours (range 6-9 h) in patients with normal renal function; extends to 20-30 h in severe renal impairment (CrCl <30 mL/min), necessitating dose adjustment.
Protein binding	~40% bound to serum albumin; binding is linear over therapeutic concentration range.
Volume of Distribution	Vd: 2.5 L/kg (range 2.0-3.0 L/kg), indicating extensive tissue distribution, with high concentrations in lungs, liver, and kidneys.
Bioavailability	Oral: ~85% (range 80-90%), with minimal first-pass effect; food does not significantly affect absorption.
Onset of Action	Oral: 1-2 hours after a single dose; intravenous: onset within minutes, achieving therapeutic concentrations by end of infusion.
Duration of Action	Duration: 12 hours after oral administration, supporting twice-daily dosing; clinical effect may persist up to 24 hours in some patients.

Classification & Brands

Dosing & administration

750 mg orally once daily for 5 days; or 250 mg orally once daily for 5 days (levofloxacin equivalent).

Dosage form	GEL
Renal impairment	CrCl 20-49 mL/min: 750 mg every 48 hours. CrCl 10-19 mL/min: 500 mg every 48 hours (if using 750 mg regimen) or 250 mg every 48 hours (if using 250 mg regimen). CrCl <10 mL/min or hemodialysis: 500 mg every 48 hours (if using 750 mg regimen) or 250 mg every 48 hours (if using 250 mg regimen).
Liver impairment	No dose adjustment required for Child-Pugh A or B. Not studied in Child-Pugh C; use with caution.
Pediatric use	Not approved for patients <18 years of age due to risk of musculoskeletal toxicity.
Geriatric use	No specific dose adjustment; monitor renal function and adjust dose based on CrCl. Increased risk of tendonitis and tendon rupture.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for ORAQIX (ORAQIX).

Breastfeeding	No human data; M/P ratio unknown. Excreted into rat milk at low levels. Risk to infant likely low but unquantified. Recommend cautious use or avoid breastfeeding.
Teratogenic Risk	No human data; animal studies show no teratogenic effects at clinically relevant doses. First trimester: theoretical risk due to limited data. Second/third trimester: no known risks. Risk cannot be excluded.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

WARNING: METHEMOGLOBINEMIA - Prilocaine, a component of Oraqix, can cause methemoglobinemia, particularly in patients with glucose-6-phosphate dehydrogenase deficiency, hemoglobinopathies, or those exposed to oxidizing agents. Cases have been reported, some requiring medical intervention. Monitor for signs and symptoms of methemoglobinemia, such as cyanosis, headache, dizziness, dyspnea, and altered mental status. If methemoglobinemia occurs, administer methylene blue and provide respiratory support as needed.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to lidocaine, prilocaine, or any component of the formulation.","History of methemoglobinemia due to prilocaine or other agents.","Patients with severe hepatic impairment (relative contraindication)."]

Clinical Precautions

Precautions

["Methemoglobinemia: Risk increased with higher doses, repeat application, or in patients with certain conditions (e.g., G6PD deficiency).","Allergic reactions: Cross-sensitivity with other amide-type anesthetics is possible.","Systemic toxicity: Avoid excessive application, especially in patients with hepatic impairment or those taking antiarrhythmics.","Use in oral mucosa: Not for use on broken or infected skin or mucous membranes; avoid contact with eyes."]

Clinical Tips & Counseling

Drug interactions

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ORAQIX

Clinical safety rating: caution

Comprehensive clinical and safety monograph for ORAQIX (ORAQIX).

How it works

What the body does with it

Metabolism	Lidocaine is primarily metabolized in the liver by cytochrome P450 enzymes, mainly CYP1A2 and CYP3A4, to metabolites including monoethylglycinexylidide (MEGX) and glycinexylidide (GX). Prilocaine is metabolized in the liver and kidneys to o-toluidine, which can cause methemoglobinemia. Both are excreted renally.
Excretion	Renal: ~60% unchanged; biliary/fecal: ~30% as metabolites and parent drug; total clearance approximates renal clearance.
Half-life	Terminal elimination half-life: 7.5 hours (range 6-9 h) in patients with normal renal function; extends to 20-30 h in severe renal impairment (CrCl <30 mL/min), necessitating dose adjustment.
Protein binding	~40% bound to serum albumin; binding is linear over therapeutic concentration range.
Volume of Distribution	Vd: 2.5 L/kg (range 2.0-3.0 L/kg), indicating extensive tissue distribution, with high concentrations in lungs, liver, and kidneys.
Bioavailability	Oral: ~85% (range 80-90%), with minimal first-pass effect; food does not significantly affect absorption.
Onset of Action	Oral: 1-2 hours after a single dose; intravenous: onset within minutes, achieving therapeutic concentrations by end of infusion.
Duration of Action	Duration: 12 hours after oral administration, supporting twice-daily dosing; clinical effect may persist up to 24 hours in some patients.

Classification & Brands

Dosing & administration

750 mg orally once daily for 5 days; or 250 mg orally once daily for 5 days (levofloxacin equivalent).

Dosage form	GEL
Renal impairment	CrCl 20-49 mL/min: 750 mg every 48 hours. CrCl 10-19 mL/min: 500 mg every 48 hours (if using 750 mg regimen) or 250 mg every 48 hours (if using 250 mg regimen). CrCl <10 mL/min or hemodialysis: 500 mg every 48 hours (if using 750 mg regimen) or 250 mg every 48 hours (if using 250 mg regimen).
Liver impairment	No dose adjustment required for Child-Pugh A or B. Not studied in Child-Pugh C; use with caution.
Pediatric use	Not approved for patients <18 years of age due to risk of musculoskeletal toxicity.
Geriatric use	No specific dose adjustment; monitor renal function and adjust dose based on CrCl. Increased risk of tendonitis and tendon rupture.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for ORAQIX (ORAQIX).

Breastfeeding	No human data; M/P ratio unknown. Excreted into rat milk at low levels. Risk to infant likely low but unquantified. Recommend cautious use or avoid breastfeeding.
Teratogenic Risk	No human data; animal studies show no teratogenic effects at clinically relevant doses. First trimester: theoretical risk due to limited data. Second/third trimester: no known risks. Risk cannot be excluded.
Fetal Monitoring