MYCOPHENOLATE MOFETIL HYDROCHLORIDE
Clinical safety rating: avoid
Antacids and cholestyramine can decrease absorption Can cause severe myelosuppression and increased risk of infections.
Mycophenolate mofetil hydrochloride is a prodrug of mycophenolic acid (MPA), a selective, reversible inhibitor of inosine monophosphate dehydrogenase (IMPDH). This enzyme is crucial for de novo guanosine nucleotide synthesis in T and B lymphocytes, leading to inhibition of lymphocyte proliferation and antibody production.
| Metabolism | Mycophenolate mofetil is rapidly hydrolyzed by esterases to the active metabolite mycophenolic acid (MPA). MPA is primarily metabolized by glucuronidation via UGT1A9 and UGT1A8 to the inactive phenolic glucuronide (MPAG), which is excreted in urine. Enterohepatic recirculation of MPAG contributes to MPA levels. |
| Excretion | Mycophenolic acid (MPA), the active metabolite, is primarily excreted in urine as the glucuronide conjugate (MPAG). Approximately 87% of an administered dose is recovered in urine, with <1% as unchanged MPA. Fecal excretion accounts for about 6% of the dose, mainly as MPAG via biliary secretion. |
| Half-life | The terminal elimination half-life of MPA is approximately 17.9 hours (range 11.7–30.9 hours) in healthy volunteers. In renal transplant patients, half-life may be prolonged to 16.6 ± 6.2 hours. This supports twice-daily dosing with monitoring of trough levels for efficacy and toxicity. |
| Protein binding | Mycophenolic acid is highly protein bound (approximately 97%) to serum albumin, primarily at drug-binding site II. In patients with renal impairment or hypoalbuminemia, free fraction increases, potentially enhancing pharmacodynamic effect and toxicity. |
| Volume of Distribution | The apparent volume of distribution at steady state (Vdss) is approximately 3.6 L/kg (range 1.5–5 L/kg). This large Vd indicates extensive tissue distribution, with highest concentrations in kidney, liver, and gastrointestinal tract, consistent with its immunosuppressive targets. |
| Bioavailability | Oral bioavailability of mycophenolate mofetil is approximately 94% (range 88–97%) relative to intravenous dosing, based on MPA AUC. Absorption is rapid and nearly complete; food reduces MPA Cmax by 40% but does not significantly affect AUC. |
| Onset of Action | Oral: Clinical immunosuppressive effect begins within hours; peak inhibition of inosine monophosphate dehydrogenase (IMPDH) occurs 1–2 hours post-dose. Intravenous: Rapid onset with peak concentrations at the end of infusion; clinical effect correlates with MPA AUC. |
| Duration of Action | Duration of action is typically 12 hours, consistent with dosing interval. Immunosuppressive effect persists as long as MPA concentrations remain above therapeutic threshold (AUC 30–60 mg·h/L). Recovery of lymphocyte function occurs after drug clearance. |
Oral: 1-1.5 g twice daily; intravenous: 1 g over 2 hours twice daily.
| Dosage form | INJECTABLE |
| Renal impairment | GFR > 25 mL/min: no adjustment; GFR 10-25 mL/min: maximum 1 g twice daily; GFR < 10 mL/min: avoid use. |
| Liver impairment | No adjustment required for mild to moderate hepatic impairment; severe hepatic impairment (Child-Pugh >10): no data. |
| Pediatric use | Oral suspension: 600 mg/m2 twice daily; maximum 1 g twice daily; intravenous: same dose as oral. |
| Geriatric use | No specific adjustment; use lowest effective dose due to increased infection risk. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Antacids and cholestyramine can decrease absorption Can cause severe myelosuppression and increased risk of infections.
| FDA category | Contraindicated |
| Breastfeeding | Considered contraindicated due to potential for serious adverse reactions in breastfed infants. M/P ratio not established; drug partitions into breast milk in limited animal data. Recommend avoiding breastfeeding during therapy and for 6 weeks after last dose. |
| Teratogenic Risk | Pregnancy Category D. First trimester: High risk of structural malformations (cleft lip/palate, microtia, cardiac defects) and miscarriage. Second/third trimester: Risk of intrauterine growth restriction, low birth weight, and preterm delivery. Postnatal: Potential for immunosuppression and infections in the neonate. |
■ FDA Black Box Warning
Increased risk of congenital malformations (including facial, cardiac, and CNS defects) and first-trimester pregnancy loss when used during pregnancy. Females of reproductive potential must use effective contraception before, during, and for 6 weeks after therapy. Also associated with increased risk of lymphomas and other malignancies, particularly skin cancers.
| Common Effects | autoimmune disorders |
| Serious Effects |
Hypersensitivity to mycophenolate mofetil, mycophenolic acid, or any component; pregnancy (absolute); women of reproductive potential not using effective contraception; concomitant use with azathioprine (relative); active serious infections (relative); severe hepatic impairment (relative).
| Precautions | Risk of immunosuppression leading to opportunistic infections (including CMV, BK virus, and tuberculosis); increased risk of lymphoproliferative disorders; severe neutropenia (monitor CBC); gastrointestinal bleeding and perforation; avoid live vaccines; interaction with azathioprine (avoid concomitant use); dose adjustment in renal impairment. |
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| Fetal Monitoring | Monitor maternal complete blood counts, renal function, and liver enzymes monthly. Fetal ultrasound for structural anomalies at 18-20 weeks. Serial growth scans for fetal growth restriction. Monitor neonates for infections and bone marrow suppression. |
| Fertility Effects | Reversible impairment of spermatogenesis (males) and menstrual irregularities (females). No definitive evidence of permanent infertility. Contraception counseling recommended during treatment and for 6 weeks post-therapy. |