Serum retinoids in retinitis pigmentosa patients treated with vitamin A.
BACKGROUND
Patients with retinitis pigmentosa have been suggested to benefit from treatment with moderate doses of retinyl palmitate. Retinyl palmitate is not an active retinoid in itself but is metabolised to active components in the body. To find out which metabolites of retinyl palmitate were formed and at which concentrations, we measured the concentrations of retinol, retinyl palmitate, retinoic acids and tocopherol in serum of patients treated with oral retinyl palmitate for retinitis pigmentosa.


METHODS
Nine male patients and one female diagnosed as having retinitis pigmentosa after a complete ophthalmological examination including a full-field electroretinogram were given vitamin A at their own request as one daily morning dose of 16600 IU vitamin A. Blood samples were obtained before and after > 2 weeks of treatment. The concentrations of retinoids and tocopherol were measured with established methods.


RESULTS
The patients were not deficient in vitamin A or vitamin E as judged from the serum vitamin concentrations. Treatment with retinyl palmitate significantly increased the serum concentration of retinyl palmitate and of 13-cis-retinoic acid but not of retinol, tocopherol or all-trans-retinoic acid.


CONCLUSIONS
Neither retinyl palmitate nor 13-cis-retinoic acid, are known to be biologically active. However, 13-cis-retinoic acid can isomerise to the active vitamin A derivative, all-trans-retinoic acid. It is suggested that patients may be treated with a small dose of 13-cis-retinoic acid instead, to avoid the relatively long metabolic detour from retinyl palmitate.
Fex
G A
GA
Department of Clinical Chemistry, Lund University Hospital, Sweden.
Andréasson
S
S
Ehinger
B
B
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D016588:Anticarcinogenic Agents / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D004224:Diterpenes; D004596:Electroretinography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012174:Retinitis Pigmentosa / Q000097:blood* / Q000188:drug therapy / Q000503:physiopathology; D012176:Retinoids / Q000097:blood*; D000084562:Retinyl Esters; D014212:Tretinoin / Q000031:analogs & derivatives / Q000097:blood; D014801:Vitamin A / Q000031:analogs & derivatives / Q000097:blood / Q000627:therapeutic use*; D014810:Vitamin E / Q000097:blood
D016588:Anticarcinogenic Agents; D004224:Diterpenes; D012176:Retinoids; D000084562:Retinyl Esters; D014801:Vitamin A; D014810:Vitamin E; C014794:retinol palmitate; C002202:4-oxoretinoic acid; D014212:Tretinoin