MEZOFY
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MEZOFY (MEZOFY).
MEZOFY is a selective serotonin reuptake inhibitor (SSRI) that potentiates serotonergic activity in the CNS by inhibiting the reuptake of serotonin at the presynaptic neuronal membrane.
| Metabolism | Extensively metabolized in the liver via CYP2D6 and CYP3A4 isoenzymes to the active metabolite N-desmethylmezofy. Metabolites are further glucuronidated and excreted renally. |
| Excretion | Renal: 60% unchanged; biliary/fecal: 25% as metabolites; 15% other |
| Half-life | Terminal half-life: 8-12 hours (mean 10 h); prolonged in renal impairment (up to 24 h in CrCl <30 mL/min) |
| Protein binding | 95% bound primarily to albumin; also to alpha-1-acid glycoprotein |
| Volume of Distribution | 0.3-0.4 L/kg (approx 21-28 L in 70 kg adult); indicates moderate tissue distribution |
| Bioavailability | Oral: 80-90% (tablet); 70-80% (suspension); IM: 100% |
| Onset of Action | Oral: 1-2 hours; IV: 5-10 minutes; IM: 15-30 minutes |
| Duration of Action | 4-6 hours (oral); 6-8 hours (IV); clinical effect correlates with plasma levels above 2 mcg/mL |
MEZOFY (mexiletine) 200 mg orally every 8 hours; may increase to 300 mg every 8 hours if needed.
| Dosage form | FILM |
| Renal impairment | If GFR < 30 mL/min: administer 75% of normal dose; if GFR < 10 mL/min: administer 50% of normal dose. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 25%; Child-Pugh C: reduce dose by 50%. |
| Pediatric use | No established pediatric dosing; use not recommended. |
| Geriatric use | Start at lower end of dosing range (200 mg every 8-12 hours); monitor for CNS and cardiovascular adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MEZOFY (MEZOFY).
| Breastfeeding | Excreted in breast milk; M/P ratio 0.8. Consider risk-benefit; monitor infant for renal adverse effects. |
| Teratogenic Risk | First trimester: Limited data; animal studies show embryotoxicity at high doses. Second and third trimesters: Risk of impaired renal function and oligohydramnios; avoid unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal blood pressure, renal function, electrolytes. Fetal ultrasound for amniotic fluid volume and growth. |
■ FDA Black Box Warning
Increased risk of suicidal thoughts and behavior in children, adolescents, and young adults taking antidepressants. MEZOFY is not approved for use in pediatric patients.
| Serious Effects |
Concomitant use with MAOIs or within 14 days of MAOI discontinuation, concurrent use with linezolid or methylene blue, known hypersensitivity to MEZOFY or any component of the formulation, and use in patients with severe hepatic impairment.
| Precautions | Serotonin syndrome, increased risk of bleeding (especially with NSAIDs or anticoagulants), activation of mania/hypomania, hyponatremia, bone fractures, angle-closure glaucoma, sexual dysfunction, and discontinuation syndrome (with abrupt cessation). |
Loading safety data…
| Fertility Effects | Reversible inhibition of spermatogenesis in males; no human data on female fertility. |