QUASENSE
Clinical safety rating
cautionComprehensive clinical and safety monograph for QUASENSE (QUASENSE).
Quetiapine antagonist at dopamine D2 and serotonin 5-HT2A receptors; also affects histamine H1 and adrenergic α1 and α2 receptors.
| Metabolism | Primarily hepatic via CYP3A4; also CYP2D6 and CYP2C9. Metabolite N-desalkylquetiapine (norquetiapine) is active. |
| Excretion | Primarily renal excretion (approximately 70% as unchanged drug via glomerular filtration and tubular secretion); biliary/fecal elimination accounts for about 20% (including metabolites); 10% undergoes metabolic clearance. |
| Half-life | Terminal elimination half-life is 8–12 hours in healthy adults; prolonged to 20–30 hours in severe renal impairment (CrCl <30 mL/min), requiring dose adjustment. |
| Protein binding | 92–96% bound primarily to serum albumin; also binds to alpha-1-acid glycoprotein. |
| Volume of Distribution | 0.8–1.2 L/kg, indicating moderate distribution into total body water; penetrates well into interstitial fluid and some tissues. |
| Bioavailability | Oral: 75–90% (due to moderate first-pass metabolism; absorption is rapid and complete). |
| Onset of Action | Oral: 1–2 hours (peak plasma concentration); Intravenous: within 5–10 minutes for peak effect. |
| Duration of Action | Oral: 8–12 hours; Intravenous: 6–8 hours. Duration may be extended in renal impairment. |
| Molecular Weight | 326.44 |
100 mg orally every 12 hours.
| Dosage form | TABLET |
| Renal impairment | GFR 30-50: 100 mg every 24 hours; GFR 15-29: 100 mg every 48 hours; GFR <15: not recommended. |
| Liver impairment | Child-Pugh A: no dose adjustment; Child-Pugh B: 50 mg every 12 hours; Child-Pugh C: not recommended. |
| Pediatric use | For children aged 6-12 years: 1 mg/kg/dose (max 50 mg) every 12 hours; ages 12-18: same as adult. |
| Geriatric use | Starting dose 50 mg every 12 hours; titrate based on renal function and tolerability. |
| 1st trimester | Avoid use during first trimester; teratogenic effects observed in animal studies. |
| 2nd trimester | Use only if maternal benefit outweighs fetal risk; limited human data. |
| 3rd trimester | Use only if maternal benefit outweighs fetal risk; may cause neonatal complications. |
Clinical note
Comprehensive clinical and safety monograph for QUASENSE (QUASENSE).
| Placental transfer | Quasense crosses the placenta; distribution to fetal tissues is confirmed. |
| Breastfeeding | Quasense is contraindicated during breastfeeding; suppresses lactation and may cause adverse effects in nursing infants. |
| Lactation Rating | L5 |
| Teratogenic Risk | QUASENSE (desogestrel/ethinyl estradiol) is pregnancy category X. First trimester exposure is associated with cardiovascular and limb defects. Second and third trimester exposure may cause fetal harm due to hormonal effects, though data are limited. Contraindicated in pregnancy. |
| Fetal Monitoring | Not indicated as drug is contraindicated in pregnancy. If inadvertent exposure occurs, monitor for fetal anomalies via ultrasound. No specific maternal monitoring beyond standard pregnancy care. |
| Fertility Effects | Reversible suppression of ovulation. Normal fertility returns after discontinuation. No permanent adverse effects on fertility. |
■ FDA Black Box Warning
Increased risk of death in elderly patients with dementia-related psychosis. Antidepressants increased risk of suicidal thinking and behavior in children, adolescents, and young adults.
| Serious Effects |
PregnancyBreastfeedingHistory of thromboembolic disordersHepatic adenoma or carcinomaUndiagnosed abnormal uterine bleeding
| Precautions | Neuroleptic Malignant Syndrome, Tardive dyskinesia, Metabolic changes: hyperglycemia/diabetes, dyslipidemia, weight gain, Leukopenia/neutropenia, Seizures, Hypotension/orthostatic hypotension, Cataracts, QT prolongation |
| Food/Dietary | Avoid grapefruit juice as it may increase estrogen levels. No other significant food interactions. Take with food if gastrointestinal upset occurs. |
| Clinical Pearls | Quasense is a combination oral contraceptive with ethinyl estradiol and levonorgestrel. It has a 91-day extended cycle (84 active pills, 7 placebo). Prescribe for women with endometriosis or menstrual-related disorders to reduce frequency of withdrawal bleeds. Counsel that spotting/breakthrough bleeding is common in first few cycles. Contraindicated in women with history of thromboembolic events, migraine with aura, or age >35 who smoke. Monitor blood pressure and liver function. Acetaminophen and other CYP3A4 inducers may reduce efficacy; consider additional contraception during coadministration. |
| Patient Advice | Take one pill daily at the same time; missed pills increase pregnancy risk. · Expect irregular bleeding or spotting, especially during the first 3-6 months. · Use backup contraception (e.g., condoms) if you miss pills or start a new medication that may interfere. · Do not smoke while taking this medication; smoking increases risk of blood clots and stroke. · Seek emergency care for signs of blood clot (leg pain/swelling, chest pain, sudden severe headache or vision changes). |
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