Vitamin A
Retinol, Isotretinoin, Tretinoin
Also known as: Roaccutane · Isotrexin · Vitamin E suspension · Retinol · Isotretinoin · 13-cis retinoic acid · all-trans retinoic acid · Alpha-tocopherol · Tocopheryl acetate
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Reviewed non-calculator evidenceReviewed non-calculator evidence (3)
Evidence only — not for automatic calculation
[not stated in source table]
TABLE 128.6. Agent: Vitamin A (Aquasol A, 50,000 U/mL, Mayne Pharma). Dosage: 1 U/g PO daily × 14 days. Species/Comments: [not stated in source table]. Reference: 52. Table note: SC can be administered into the dorsal lymph sac of anurans..
Evidence only — not for automatic calculation
African foam-nesting frogs/weight range, 2–7 g; dosing q48h and once weekly significantly increased whole body vitamin A levels over control group and group treated with vitamin A fortified supplement dusted over crickets
TABLE 128.6. Agent: Vitamin A (Aquasol A, 50,000 U/mL, Mayne Pharma). Dosage: Dilute 1 : 10 in sterile water; applied as one drop from 18-g needle; estimated as 50 U/frog q48h to q7d. Species/Comments: African foam-nesting frogs/weight range, 2–7 g; dosing q48h and once weekly significantly increased whole body vitamin A levels over control group and group treated with vitamin A fortified supplement dusted over crickets. Reference: 39. Table note: SC can be administered into the dorsal lymph sac of anurans..
Evidence only — not for automatic calculation
Hypovitaminosis A; given the plethora of organ systems that hypovitaminosis A may affect, it is reasonable to institute vitamin A supplementation of any clinically ill amphibian, particularly ones with signs similar to “short tongue syndrome,” swollen eyelids, evidence of infectious dermatitis, hydrocoelom, or simply “failing to thrive”; the use of mixed dietary carotenoids may also be effective i
TABLE 128.6. Agent: Vitamin A (Aquasol A, 50,000 U/mL, Mayne Pharma). Dosage: Dilute 1 : 9 with sterile water; make fresh weekly; apply 1 drop from a tuberculin syringe with 27-g needle to amphibians under 5 g; 1 drop from tuberculin syringe without needle is about 200 U and useful for 15–30 g BW; >30 g, try 1 drop per 10 g BW; topically q24h × 14 days, then q4–7d. Species/Comments: Hypovitaminosis A; given the plethora of organ systems that hypovitaminosis A may affect, it is reasonable to institute vitamin A supplementation of any clinically ill amphibian, particularly ones with signs similar to “short tongue syndrome,” swollen eyelids, evidence of infectious dermatitis, hydrocoelom, or simply “failing to thrive”; the use of mixed dietary carotenoids may also be effective in some species. Reference: 52; 8. Table note: SC can be administered into the dorsal lymph sac of anurans..
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Vitamin A and its retinoid derivatives (isotretinoin, tretinoin) are fat-soluble vitamins and hormones essential for normal vision, growth, reproduction, and the maintenance of epithelial tissues. In veterinary medicine, they are primarily used to treat hypovitaminosis A and specific dermatological conditions such as sebaceous adenitis or primary seborrhoea.
WARNING: Retinoids are highly teratogenic. Extreme caution must be exercised by both the prescribing veterinarian and the pet owner to prevent accidental exposure, particularly to pregnant women.
Mechanism of action
Acts as a nutritional fat-soluble hormone that regulates gene expression.
Tretinoin (all-trans retinoic acid) is the acid form of vitamin A, and isotretinoin (13-cis retinoic acid) is an isomer of tretinoin.
Clinical Pearl: They bind to intracellular retinoic acid receptors (RARs) and retinoid X receptors (RXRs) → modifying gene transcription → regulating epithelial cell growth, differentiation, and sebum production.
Safety & warnings
Contraindications
- Pregnant animals
- Breeding animals
- Patients at high risk for thrombosis
- Neonates
Adverse effects
- Teratogenicity (fetal malformations)
- Keratoconjunctivitis sicca (KCS / dry eye)
- Hepatotoxicity
- Hyperlipidaemia
- Hypercalcaemia (due to bone calcium loss with prolonged use)
- Skin redness and pigmentation
- Haematological abnormalities
- Nervous system changes
- Bone changes
- Thrombosis
- Anaphylactoid reactions
Precautions
TERATOGENIC WARNING: Gloves should be worn when applying topical preparations. Pregnant women should avoid handling these medications entirely.
- Avoid contact with eyes, mouth, or mucous membranes.
- Avoid concurrent use of oral and topical preparations due to cumulative toxicity.
- Do not use formulations of vitamins A, D3, and E authorized for farm animals or horses in small animals, as they are too concentrated and risk severe toxicity.
- Minimize exposure of the drug to sunlight.
Drug interactions
Oral vitamin A may alter ciclosporin levels; requires close monitoring.
Do not use topical vitamin A preparations simultaneously with other topical drugs.
May enhance vitamin A absorption, utilization, and storage.
Monitoring
- Signs of vitamin A toxicity
- Tear production (Schirmer Tear Test) for KCS
- Liver enzymes (ALT, AST, ALP)
- Serum calcium levels
- Serum triglycerides/lipids
- Ciclosporin levels (if used concurrently)
- Ciclosporin blood levels (if used concurrently)
- Coagulation parameters (in patients at risk for thrombosis)
- Liver enzymes (if treating hepatopathy)
Pharmacokinetics
Half-life
Absorption
Requires bile and dietary fat for optimal intestinal absorption.
Distribution
Widely distributed; stored primarily in adipose tissue, liver, and muscle.
Metabolism
Metabolized in the liver.
Elimination
Excreted primarily in feces via bile; a small amount is excreted in urine.
Overdose
High doses or prolonged use can lead to severe vitamin A toxicity.
Signs of toxicity include:
- Hepatotoxicity
- Hyperlipidaemia
- Hypercalcaemia (due to promotion of calcium loss from bone)
- Severe skin, haematological, and nervous system abnormalities.
Treatment: Discontinue the drug immediately and provide supportive care. Monitor liver enzymes and serum calcium.
Available products
Formulations
- Injectable: 50,000 IU/ml (retinol)
- Oral capsules: 10 mg, 20 mg (isotretinoin)
- Topical gel: 0.05% (isotretinoin)
- Oral suspension: 20 mg/ml
- Oral suspension: 100 mg/ml
- Injectable preparations (often combined with selenium for large animals)
- Nutraceuticals (often combined with SAMe)
Veterinary
- Vitamin E suspension 20 mg/ml (POM-VPS)
- Vitamin E suspension 100 mg/ml (POM-VPS)
- Various nutraceutical combinations (e.g., with SAMe)
Human-labeled
- Roaccutane (10 mg, 20 mg isotretinoin capsules)
- Isotrex (0.05% isotretinoin gel)
- Isotrexin (0.05% isotretinoin gel)
- Various oral capsules and liquid preparations
Regulatory status
Classified as POM-VPS in some regions for specific veterinary formulations.
Classified as POM-VPS.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Minimize exposure of the drug to sunlight.
Client information
CRITICAL WARNING: This medication can cause severe birth defects. Pregnant women or women trying to conceive must absolutely not handle this medication or the pet's treated skin.
- Always wear disposable gloves when applying the topical gel.
- Do not use this medication if your pet is pregnant or intended for breeding.
- Watch your pet's eyes closely; this drug can change the lipid content of tears and cause severe dry eye. Contact your vet if you notice squinting, redness, or thick eye discharge.
- Keep the medication out of direct sunlight.
- Do not apply other topical medications to the same area unless instructed by your veterinarian.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.