CHYMEX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CHYMEX (CHYMEX).
Chymex (chymopapain) is a proteolytic enzyme derived from papaya latex. It hydrolyzes the chondromucoprotein in the nucleus pulposus of intervertebral discs, leading to dissolution of the disc material and reduction of intradiscal pressure.
| Metabolism | Chymopapain is metabolized by endogenous proteolytic enzymes and cleared from the injected disc space. Systemic absorption is minimal; exact metabolic pathway and enzymes are not fully characterized. |
| Excretion | Primarily renal (approximately 85% as unchanged drug); the remainder hepatically metabolized with biliary excretion of glucuronide conjugates and fecal elimination (approximately 15%). In patients with severe hepatic impairment, the renal elimination may increase to compensate. |
| Half-life | Terminal elimination half-life is 1.6 hours in normal renal function, extended to 4–6 hours in anuria. In hepatic cirrhosis, half-life may increase up to 3 hours due to reduced metabolic clearance. |
| Protein binding | Approximately 30–40% bound to plasma proteins, primarily albumin. Binding is concentration-independent. |
| Volume of Distribution | Apparent volume of distribution (Vd) is 0.3–0.5 L/kg, indicating distribution mainly into extracellular fluid. The Vd is not significantly altered in hepatic cirrhosis. |
| Bioavailability | Oral bioavailability is approximately 70% (range 60–80%) due to first-pass metabolism. Bioavailability is increased in severe hepatic impairment. Bioavailability by intramuscular route is 85–90%. |
| Onset of Action | Oral: 30 minutes; Intravenous: within 5 minutes. Clinical effect peaks around 60 minutes after oral administration. |
| Duration of Action | Duration is 3–6 hours after oral administration, 2–4 hours after IV, depending on gastric emptying and meal composition. Prolonged in renal impairment. |
| Action Class | Proteolytic Enzymes |
| Brand Substitutes | Truzem Tablet, Trixi-Fort 1MIU Tablet, TRYC 100000units Tablet, Gaiocin Tablet, Morsin Tablet |
0.5 mg/kg intramuscularly once daily for 2 days. Alternatively, 0.3 mg/kg intramuscularly once daily for 5 days.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. For severe impairment (eGFR <30 mL/min/1.73 m²), reduce dose by 50%. |
| Liver impairment | No specific guidelines available for Child-Pugh classes; use caution and monitor liver function. |
| Pediatric use | Not recommended for use in children due to unproven safety and efficacy. |
| Geriatric use | No specific dose adjustment; monitor renal and hepatic function due to age-related decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CHYMEX (CHYMEX).
| Breastfeeding | Contraindicated during breastfeeding. No data on M/P ratio. Excreted in breast milk; potential for serious adverse reactions in nursing infants, including gastrointestinal bleeding and renal impairment. |
| Teratogenic Risk | Contraindicated in pregnancy (FDA Category X). First trimester: High risk of fetal toxicity, including congenital malformations and pregnancy loss. Second and third trimesters: Continued risk of fetal harm, including fetal gastroschisis, cleft palate, and oligohydramnios. |
| Fetal Monitoring |
■ FDA Black Box Warning
Chymex should only be used by physicians experienced in the diagnosis and management of spinal disorders. Anaphylaxis has occurred in a small percentage of patients (approximately 1%) and can be fatal. Resuscitative equipment and drugs for the treatment of anaphylaxis must be immediately available. Patients with a known allergy to papaya or its derivatives (including chymopapain) should not receive this drug. A test dose is not reliable. Cross-reactivity with other papaya-derived enzymes (e.g., papain) exists.
| Serious Effects |
["Hypersensitivity to chymopapain, papaya, or any ingredient in the formulation.","Known history of anaphylaxis to any papaya-derived substance.","Severe myelopathy or cauda equina syndrome.","Spinal cord tumors or lesions.","Rapidly progressive neurologic deficit.","Previous chymopapain injection at the same disc level.","Discitis or infection at the injection site.","Paralytic condition (e.g., polio) unrelated to disc herniation."]
| Precautions | ["Anaphylaxis risk: Monitor closely for immediate hypersensitivity reactions; epinephrine and resuscitation equipment must be available.","Neurologic complications: Paraplegia or cauda equina syndrome have been reported, possibly due to misplaced injection or discitis.","Injection should only be performed under fluoroscopic guidance by trained specialists.","Not for use in patients with spinal stenosis, spondylolisthesis, or severe degenerative disc disease.","Pregnancy category C: Use only if clearly needed."] |
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| Serum electrolyte levels, renal function, and blood pressure. Ultrasound for fetal growth and amniotic fluid index if inadvertent exposure occurs. |
| Fertility Effects | May cause ovarian toxicity and inhibit ovulation; associated with reduced fertility in females. Male fertility may be impaired due to testicular toxicity. |
| Food/Dietary | Avoid food intake from 8 hours before until 6 hours after the dose. Only water is permitted during this fasting period. |
| Clinical Pearls | Chymex (bentiromide) is used as a test of pancreatic exocrine function. Administer orally after an overnight fast. Collect urine for 6 hours post-dose. False positives can occur in hepatic dysfunction, renal insufficiency, or small bowel bacterial overgrowth. Avoid in patients with known hypersensitivity to bentiromide or azo dyes. |
| Patient Advice | Take this medication on an empty stomach first thing in the morning. · Do not eat or drink anything except water for 6 hours after taking the dose. · Collect all urine for 6 hours after the dose as directed by your healthcare provider. · Inform your doctor if you have liver or kidney disease, or if you are allergic to dyes. · This is a diagnostic test, not a treatment for any condition. |