Retinol (vitamin A) is an essential supplement for vision, the immune system and skin. In Angola, periodic supplementation in children is a national public health strategy against vitamin A deficiency.
Also known as: Vitamina A, Aquasol A
No documented drug–drug interactions for this medicine.
Vitamin A is fat-soluble — absorption improves substantially with dietary fat.
Take with a meal containing fat.
Prontuário Terapêutico INFARMED, 8 (fat-soluble vitamins — absorption with fat).
High-dose vitamin A is teratogenic — contraindicated in pregnancy; programme doses (50,000–200,000 IU) follow their own schedule.
Contraception in women of childbearing age on high-dose treatment; follow the national programme schedule.
Site monograph (retinol — contraindicated at high dose in pregnancy).
Vitamin A accumulates in the liver — hepatotoxicity risk at high doses in liver patients.
Avoid high doses in liver disease; monitor transaminases.
Prontuário 8 (vitamins — vitamin A hepatotoxicity at high dose).
Retinol (vitamin A) at physiological doses is required for fetal development, but excessive doses are teratogenic: the Prontuário records "toxicity in animal studies" (factor CM) and "excessive doses are teratogenic". Exposure to high doses (>10,000–25,000 IU/day) is associated with neural tube defects, craniofacial, cardiac and CNS anomalies.
Avoid supraphysiological doses in all trimesters; supplementation should only occur in documented deficiency and within safety limits. "It is unknown whether it is dangerous; the manufacturer recommends avoiding unless essential" (Annex 1).
Theoretical risk of toxicity if mothers take high doses (Prontuário, Annex 2); at normal physiological/supplementary doses breastfeeding is safe and breast-milk vitamin A benefits the infant.
Prontuário Terapêutico INFARMED — Annex 1: "Retinol — Avoid; toxicity in animal studies (CM)"; "Retinol (vitamin A) — unknown if dangerous; avoid unless essential"; "excessive doses teratogenic"; Annex 2: "Theoretical risk of toxicity if mothers take high doses". 11.3.1.1 (Fat-soluble vitamins).
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Vitamin A essential for vision, epithelial differentiation and immunity; periodic child supplementation is one of the most cost-effective public health interventions in deficiency-endemic countries.
After reduction to retinal and oxidation to retinoic acid, activates nuclear RAR/RXR receptors regulating transcription of epithelial differentiation, immune and metabolic genes; in the retina, 11-cis-retinal is the rhodopsin chromophore (twilight vision). Adjuvant role in humoral and cellular immune response (reduced measles mortality).
Requires bile and dietary fat (chylomicron transport and lymphatic route); acetate/palmitate bioavailability ~70–90% with food; water-miscible form (miscible palmitate) for parenteral use in severe malabsorption. Zinc and proteins are transport cofactors (RBP).
Ester hydrolysis in the intestinal mucosa; interconverting oxidation/reduction between retinol/retinal; hepatic esterification (palmitate) for storage in stellate cells; final oxidation to retinoic acids excreted in bile and urine as glucuronides. High doses: esterification saturation and toxicity from free retinol.
Short plasma half-life (hours) but enormous hepatic depot (90% of reserves, equivalent to months/years) — clinical deficiency only appears when hepatic stores are exhausted.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
