VITAMIN A PALMITATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VITAMIN A PALMITATE (VITAMIN A PALMITATE).
Vitamin A palmitate is a retinoid that binds to retinoic acid receptors (RARs) and retinoid X receptors (RXRs), modulating gene transcription involved in cell growth, differentiation, and vision. It is converted to retinol and then to retinaldehyde and retinoic acid, essential for phototransduction, epithelial integrity, and immune function.
| Metabolism | Metabolized primarily in the liver to retinyl esters, which are hydrolyzed to retinol. Retinol is oxidized to retinaldehyde and retinoic acid via alcohol dehydrogenases and retinaldehyde dehydrogenases. Further conjugation with glucuronic acid and excretion in bile and urine. |
| Excretion | Primarily hepatobiliary; >90% of retinol esters and metabolites excreted in feces via bile; less than 10% renally eliminated as water-soluble metabolites (e.g., retinoic acid glucuronides). |
| Half-life | Terminal elimination half-life is approximately 7–14 days for retinol in the liver; clinical effects persist for weeks due to extensive hepatic storage. |
| Protein binding | Retinol bound to retinol-binding protein (RBP) and transthyretin (TTR); >95% bound in plasma. |
| Volume of Distribution | Apparent Vd: 0.7–1.3 L/kg, indicating extensive distribution into tissues, especially liver, adipose, and retina. |
| Bioavailability | Oral: 70–90% (dietary fat enhances absorption; bile salts required). IM: ~100%. |
| Onset of Action | Oral: Onset of clinical effect for deficiency correction is 1–2 weeks; for dermatological effects (e.g., acne) 4–8 weeks. IM: Onset similar to oral due to storage. Topical: Not applicable for palmitate; systemic effects require absorption. |
| Duration of Action | Duration: Up to 3–4 months after single high-dose oral or IM administration, due to slow release from hepatic stores and low clearance. |
| Molecular Weight | 524.86 |
Adult: 1,500-3,000 IU (450-900 mcg RAE) orally once daily for vitamin A deficiency; IM administration not recommended due to local toxicity.
| Dosage form | CAPSULE |
| Renal impairment | No dose adjustment required for renal impairment; monitor serum retinol levels in dialysis patients. |
| Liver impairment | Child-Pugh Class C: reduce dose by 50% due to impaired conversion to retinol; monitor for toxicity. |
| Pediatric use | Infants and children: 1,500-2,500 IU (450-750 mcg RAE) orally once daily; for deficiency, 5,000-10,000 IU/kg/day for 5 days, then 5,000 IU/day. |
| Geriatric use | No specific dose adjustment; monitor for hypervitaminosis A due to potential reduced clearance and increased bone fragility. |
| 1st trimester | Avoid doses exceeding RDA (3000 IU/day) due to risk of teratogenicity (CNS, heart, craniofacial defects). Upper limit 10,000 IU/day. |
| 2nd trimester | Avoid excessive doses; RDA 3000 IU/day; high doses may cause hepatotoxicity and pseudotumor cerebri. |
| 3rd trimester | Avoid excessive doses; RDA 3000 IU/day; high doses associated with neonatal hypervitaminosis A and craniotabes. |
Clinical note
Comprehensive clinical and safety monograph for VITAMIN A PALMITATE (VITAMIN A PALMITATE).
| Placental transfer | Crosses placenta; maternal levels correlate with fetal levels; excessive accumulation in fetal liver. |
| Breastfeeding | Vitamin A is excreted into breast milk; RDA during lactation 4000-5000 IU/day. High doses (>10,000 IU/day) may cause toxicity in infant; caution with massive supplementation (e.g., 200,000 IU) in early postpartum. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypervitaminosis AHypersensitivity to vitamin A or any componentSevere hepatic impairment (relative)Pregnancy with doses > RDA (10,000 IU/day) due to teratogenicity
| Precautions | Hypervitaminosis A: acute and chronic toxicity (hepatotoxicity, pseudotumor cerebri, teratogenicity), Hepatotoxicity: monitor liver enzymes in long-term use, Teratogenicity: avoid in pregnancy (high doses), Bone toxicity: long-term high doses may cause osteoporosis or hyperostosis, Renal impairment: use with caution in patients with renal disease, Hypersensitivity reactions |
| Food/Dietary | Take with meals containing fat for optimal absorption. Avoid excessive alcohol intake as it may increase hepatotoxicity risk. No specific food restrictions. |
Loading safety data…
| Lactation Rating | L2 (Limited data - probably compatible) |
| Teratogenic Risk | Vitamin A palmitate is teratogenic at high doses. In the first trimester, doses >10,000 IU/day increase risk of CNS, cardiovascular, and craniofacial malformations. Second and third trimester: high doses may impair fetal growth and hepatic function. The US RDA for pregnancy is 770 mcg RAE/day (2565 IU), and toxicity is dose-dependent. Avoid doses exceeding the RDA unless treating deficiency. |
| Fetal Monitoring | Monitor serum retinol levels if high-dose therapy required; assess for signs of hypervitaminosis A (headache, blurred vision, hepatotoxicity). Fetal ultrasound if inadvertent high-dose exposure. |
| Fertility Effects | No adverse effects on fertility at physiologic doses. High doses may disrupt menstrual cycles and impair fertility via vitamin A toxicity. |
| Clinical Pearls | Hypervitaminosis A can occur with high doses; avoid exceeding 10,000 IU daily in adults. Monitor for pseudotumor cerebri symptoms (headache, visual changes). Use with caution in patients with hepatic impairment. Fat-soluble vitamin; absorption increases with dietary fat. Pregnancy category X above recommended dietary allowance; teratogenic risk. |
| Patient Advice | Take with food containing fat to enhance absorption. · Do not exceed recommended dose; too much vitamin A can cause liver damage and birth defects. · Avoid taking other supplements containing vitamin A without consulting your doctor. · Report symptoms like severe headache, blurred vision, or bone pain immediately. · If pregnant or planning pregnancy, discuss with your doctor before use. |