WERA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for WERA (WERA).
WERA is a serotonin-norepinephrine reuptake inhibitor (SNRI) that inhibits the reuptake of serotonin and norepinephrine, enhancing neurotransmission in the central nervous system.
| Metabolism | Primarily metabolized by CYP2D6 and CYP3A4 to active and inactive metabolites; undergoes hepatic conjugation and renal excretion. |
| Excretion | WERA is predominantly eliminated via the renal route, with approximately 60-70% of the dose excreted unchanged in the urine. Biliary/fecal excretion accounts for 20-30% of elimination, primarily as metabolites. Less than 10% is eliminated via other routes. |
| Half-life | The terminal elimination half-life of WERA is approximately 4-6 hours in patients with normal renal function. This relatively short half-life supports twice-daily dosing, but requires dose adjustment in renal impairment. |
| Protein binding | WERA is approximately 85-90% bound to plasma proteins, primarily to albumin. Binding is concentration-independent within therapeutic range. |
| Volume of Distribution | The volume of distribution (Vd) of WERA is 1.5-2.5 L/kg, indicating extensive tissue distribution beyond plasma volume. This large Vd supports once-daily dosing for certain indications but requires loading doses for rapid attainment of steady state. |
| Bioavailability | Oral bioavailability of WERA is approximately 50-60% due to first-pass metabolism. Bioavailability is not significantly affected by food. Intramuscular bioavailability is essentially 100%. |
| Onset of Action | For intravenous administration, clinical effect is typically observed within 2-5 minutes. Oral administration results in onset within 30-60 minutes, with peak effect at 1-2 hours. Intramuscular injection provides onset within 10-15 minutes. |
| Duration of Action | Duration of action after intravenous administration is approximately 4-6 hours. Oral dosing provides duration of 6-8 hours due to sustained absorption. Effects may be prolonged in patients with hepatic impairment. |
10-20 mg orally once daily
| Dosage form | TABLET |
| Renal impairment | eGFR 30-89 mL/min: no adjustment; eGFR <30 mL/min: use 50% of standard dose or increase dosing interval to every other day |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated |
| Pediatric use | 0.2-0.4 mg/kg/day orally in divided doses twice daily; maximum 20 mg/day |
| Geriatric use | Initiate at 5 mg orally once daily; titrate cautiously to a maximum of 10 mg/day |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for WERA (WERA).
| Breastfeeding | Excretion into human milk is unknown; animal studies show low levels. M/P ratio is not established. Due to risk of bleeding in the infant, breastfeeding is not recommended during WERA therapy. |
| Teratogenic Risk | WERA is a direct-acting oral anticoagulant; based on animal studies and limited human data, there is a risk of hemorrhage and teratogenicity, particularly in the first trimester. Fetal risks include spontaneous abortion, premature delivery, and fetal bleeding. In the second and third trimesters, risks include placental abruption and fetal intracranial hemorrhage. Use is contraindicated in pregnancy unless no suitable alternative exists. |
■ FDA Black Box Warning
WARNING: SUICIDAL THOUGHTS AND BEHAVIORS - Antidepressants increased the risk of suicidal thoughts and behavior in children, adolescents, and young adults in short-term studies. Closely monitor for clinical worsening, suicidality, or unusual changes in behavior. WERA is not approved for use in pediatric patients.
| Serious Effects |
Concomitant use with MAOIs or within 14 days of MAOI therapy; hypersensitivity to WERA or any component; uncontrolled angle-closure glaucoma.
| Precautions | Serotonin syndrome; elevated blood pressure; angle-closure glaucoma; activation of mania/hypomania; seizures; hyponatremia; abnormal bleeding; discontinuation syndrome; hepatotoxicity; sexual dysfunction; weight changes. |
Loading safety data…
| Fetal Monitoring | Monitor maternal coagulation parameters (aPTT, anti-Xa activity if available) regularly. Assess for signs of bleeding: petechiae, ecchymosis, hematuria, gingival bleeding. Perform fetal ultrasound for growth and anatomy, especially placental appearance and signs of hemorrhage. Monitor fetal heart rate pattern for distress if bleeding suspected. |
| Fertility Effects | No clinically significant effects on fertility documented in animal studies. In humans, limited data suggest no adverse impact on spermatogenesis or ovarian function. However, anticoagulation may complicate early pregnancy recognition and management. |