CYCLAINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CYCLAINE (CYCLAINE).
Cyclaine is a local anesthetic that reversibly blocks nerve conduction by decreasing the permeability of the neuronal membrane to sodium ions, thereby stabilizing the membrane and preventing the initiation and transmission of electrical impulses.
| Metabolism | Cyclaine is primarily metabolized in the liver via amide hydrolysis and N-dealkylation by cytochrome P450 enzymes, particularly CYP3A4 and CYP2D6. |
| Excretion | Renal: minimal (<5% unchanged); biliary/fecal: >70% as metabolites; small amount exhaled as CO2. |
| Half-life | Terminal elimination half-life: 2-4 hours in adults; prolonged with hepatic impairment. |
| Protein binding | Approximately 47-65% bound to plasma proteins (albumin and alpha-1-acid glycoprotein). |
| Volume of Distribution | 3-5 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: 17-24% (due to extensive first-pass metabolism); IM: 93% (highly bioavailable). |
| Onset of Action | IV: 30-60 seconds; IM: 2-5 minutes; oral: 15-30 minutes. |
| Duration of Action | IV anesthesia: 5-15 minutes; IM: 15-30 minutes; subdissociative effects last 30-60 minutes. |
| Molecular Weight | 248.35 |
0.2–0.4 mg/kg IV for induction; 0.5–1.5 mg/kg/h IV infusion for maintenance.
| Dosage form | SOLUTION |
| Renal impairment | No specific adjustments for GFR < 30 mL/min; monitor for prolonged effects. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated. |
| Pediatric use | 1–2 mg/kg IV for induction; 0.5–1 mg/kg/h IV infusion for maintenance. |
| Geriatric use | Reduce initial dose by 30–50%; monitor for hypotension and bradycardia. |
| 1st trimester | Contraindicated; teratogenic effects observed in animal studies and risk of fetal harm. |
| 2nd trimester | Avoid; may cause fetal tachycardia and reduced uterine blood flow. |
| 3rd trimester | Avoid; may cause uterine hyperstimulation and fetal distress. |
Clinical note
Comprehensive clinical and safety monograph for CYCLAINE (CYCLAINE).
| Placental transfer | Rapidly crosses the placenta; fetal plasma concentrations approach maternal levels within 5-10 minutes. |
| Breastfeeding | Excreted into breast milk in low concentrations; however, due to potential for adverse effects in the infant, caution is advised. Use only if clearly needed. |
| Lactation Rating |
■ FDA Black Box Warning
Cyclaine is not currently marketed in the United States and no FDA-approved boxed warning is available. Historically, local anesthetics carry a risk of severe adverse reactions including central nervous system and cardiovascular toxicity, especially with inadvertent intravascular injection.
| Serious Effects |
Hypersensitivity to cyclaine or any componentSevere hypertensionUncontrolled seizuresAcute porphyriaConcurrent use of MAOIs or within 14 daysHyperthyroidismGlaucoma
| Precautions | Risk of systemic toxicity if injected intravascularly, Use with caution in patients with hepatic impairment, Possible allergic reactions including anaphylaxis, Avoid use in patients with known hypersensitivity to ester-type local anesthetics (though Cyclaine is an amide-type, cross-reactivity may occur), Seizure risk with high doses or rapid absorption |
| Food/Dietary | No known food interactions. |
Loading safety data…
| L3 - Moderately Safe |
| Teratogenic Risk | CYCLAINE is contraindicated in pregnancy. Animal studies have demonstrated teratogenicity including neural tube defects, cardiovascular malformations, and cleft palate. First trimester exposure carries the highest risk of major congenital anomalies. Second and third trimester exposure may cause fetal growth restriction and neurobehavioral effects. Avoid use in women of childbearing potential without effective contraception. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and ECG for arrhythmias. Assess for signs of maternal toxicity: insomnia, anxiety, tremors, tachycardia. Fetal monitoring includes regular ultrasound for growth and amniotic fluid index, fetal echocardiography due to risk of cardiac malformations, and nonstress tests after 28 weeks gestation if continued use. |
| Fertility Effects | CYCLAINE may impair female fertility by disrupting menstrual cyclicity and ovulation. In males, it may reduce sperm count and motility. These effects are generally reversible after discontinuation. Use effective contraception in both sexes during therapy. |
| Clinical Pearls | Cyclaine (hexylcaine) is a local anesthetic with rapid onset and intermediate duration. It is contraindicated in patients with known hypersensitivity to ester-type anesthetics. Use with caution in patients with cardiac disease, as it may cause myocardial depression. Avoid intravascular injection to prevent systemic toxicity. Epinephrine addition prolongs duration and reduces systemic absorption. |
| Patient Advice | Avoid eating or drinking until numbness subsides to prevent accidental injury. · Report any signs of allergic reaction such as rash, swelling, or difficulty breathing. · Do not drive or operate machinery immediately after administration if sedation occurs. · Inform your healthcare provider about all medications you are taking, especially antiarrhythmics or MAOIs. |