ORGATRAX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ORGATRAX (ORGATRAX).
ORGATRAX (letermovir) inhibits the cytomegalovirus (CMV) DNA terminase complex, preventing viral DNA processing and packaging.
| Metabolism | Primarily metabolized by UGT1A1/1A3, with minor contributions from CYP3A4. |
| Excretion | Primarily hepatic metabolism with renal excretion of metabolites. Approximately 30% of a dose is excreted unchanged in urine; the remainder is eliminated via feces (biliary excretion) after glucuronidation in the liver. |
| Half-life | Terminal elimination half-life is 6–8 hours in adults with normal renal and hepatic function. In elderly patients or those with hepatic impairment, half-life may be prolonged up to 12–15 hours, requiring dose adjustment. |
| Protein binding | Approximately 78–82% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd is 3–5 L/kg, indicating extensive tissue distribution. This large Vd suggests significant extravascular binding and accumulation in tissues such as lung and liver. |
| Bioavailability | Oral bioavailability is approximately 40–60% due to first-pass metabolism. Intramuscular bioavailability is near 100%. |
| Onset of Action | Oral: Onset of clinical effect occurs within 30–60 minutes for antihistaminic effects. For sedative effects, onset is 15–30 minutes. Intravenous: Onset within 5–10 minutes. |
| Duration of Action | Duration of antihistaminic effect is 4–6 hours; sedative effects last 6–8 hours. Clinical duration may be shorter in children and longer in elderly due to altered clearance. |
| Molecular Weight | 374.9 |
Hydroxyzine pamoate (Orgatrax) 25-100 mg orally every 6-8 hours as needed; maximum 600 mg/day.
| Dosage form | INJECTABLE |
| Renal impairment | For GFR <50 mL/min: administer 25 mg orally every 12 hours; monitor for excessive sedation. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh B or C: initiate at 25 mg every 12 hours and titrate cautiously due to reduced clearance. |
| Pediatric use | Children ≥6 years: 0.5-1 mg/kg orally every 6-8 hours; maximum 50 mg/day. Children <6 years: 0.5 mg/kg orally every 6-8 hours; maximum 25 mg/day. |
| Geriatric use | Initiate at 25 mg orally every 8 hours; increase slowly due to increased risk of anticholinergic effects, sedation, and falls. |
| 1st trimester | Hydroxyzine (ORGATRAX) is generally not recommended during the first trimester due to potential risk of fetal malformations based on some epidemiological studies. It should be used only if clearly needed. |
| 2nd trimester | Limited data; use only if potential benefit justifies potential risk to the fetus. Monitor for maternal sedation and hypotension. |
| 3rd trimester | Avoid use near term due to possible adverse effects on the neonate, such as respiratory depression, hypotonia, and withdrawal symptoms. |
Clinical note
Comprehensive clinical and safety monograph for ORGATRAX (ORGATRAX).
| Placental transfer | Yes, hydroxyzine crosses the placenta. Detectable levels in fetal plasma have been reported. The extent of transfer is significant, as the drug is lipophilic and has a relatively low molecular weight. |
| Breastfeeding | Hydroxyzine is excreted into human milk in small amounts. Due to potential for sedation and other effects in the nursing infant, caution is advised. Alternative agents are preferred for long-term use. Monitor infant for drowsiness, poor feeding, or irritability. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to hydroxyzine or any of its componentsPorphyriaProlonged QT interval or concurrent use of drugs that prolong QT interval (unless specifically indicated)
| Precautions | Hepatotoxicity: monitor liver function tests., Drug interactions: potent CYP3A4 inducers (e.g., rifampin) reduce letermovir exposure; coadministration with pimozide, ergot alkaloids, or HMG-CoA reductase inhibitors (simvastatin, lovastatin) contraindicated., Embryo-fetal toxicity: advise females of reproductive potential to use effective contraception during treatment and for 2 weeks after last dose., Hypersensitivity reactions. |
| Food/Dietary | Avoid concurrent consumption of alcohol; may enhance sedative effects. No specific food restrictions; however, grapefruit juice may increase hydroxyzine levels via CYP3A4 inhibition; limit grapefruit intake. |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) - Limited data, but possible adverse effects in infant. Use only if benefit outweighs risk. |
| Teratogenic Risk | FDA Pregnancy Category D (based on animal studies and limited human data). First trimester: increased risk of major malformations (cardiac, CNS), spontaneous abortion. Second/third trimester: risk of fetal growth restriction, oligohydramnios, neonatal renal impairment. Avoid in pregnancy unless benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal renal function (serum creatinine, BUN), liver function tests, and fetal growth via ultrasound. Assess amniotic fluid volume; consider fetal echocardiography if exposed in first trimester. |
| Fertility Effects | Animal studies show impairment of fertility in females (prolonged estrous cycle, reduced conception) and males (decreased sperm count, motility). Human data limited; may cause reversible menstrual irregularities or ovarian dysfunction. |
| Clinical Pearls | ORGATRAX (hydroxyzine pamoate) is an antihistamine with anxiolytic properties; monitor for QT prolongation in patients with risk factors; avoid concurrent use with CNS depressants; has a rapid onset of action (15-30 min) for pruritus; reduce dose in hepatic impairment; may cause paradoxical excitation in children or elderly; use with caution in geriatric patients due to anticholinergic effects; administer IM only as deep intramuscular injection if parenteral route required. Taper dose to avoid withdrawal symptoms after long-term use. |
| Patient Advice | Take exactly as prescribed; do not exceed recommended dose. · May cause drowsiness; avoid driving or operating machinery until effects are known. · Avoid alcohol and other CNS depressants. · Inform your doctor about all medications you are taking, especially other sedatives or anticholinergics. · Notify your physician if you experience irregular heartbeat, fainting, or severe dizziness. · Do not discontinue abruptly; your doctor may need to taper the dose. · Store at room temperature away from moisture and heat. |