DIFFERENCES IN THE BIOAVAILABILITY OF DIHYDROTACHYSTEROL PREPARATIONS

The bioavailability of four preparations containing dihydrotachysterol (DHT2) was tested in two separate trials with administration of singl e, oral doses of 1 mg per individual. The relative bioavailability of corresponding preparations (capsules vs capsules and oral solution vs oral solution) was tested in a randomised, crossover pattern within th e same group of volunteers. Two different groups of 24 healthy volunte ers took part in each trial. Solution and capsule bioavailability was also compared inter-individually. A new sensitive HPLC-method (quantif ication limit 0.5 ng . ml(-1)) was used for the measurement of DHT2 co ncentration in serum. Three of the preparations tested had a similar b ioavailability (mean AUC values of 195.5-223 ng . h . ml(-1)); the bio availability of the fourth preparation (A.T.10 oral solution) was cons iderably lower (mean AUC value 111.5 ng . h . ml(-1)). The present dos age re commendations of all four preparations are identical. A new dos age recommendation is thus required for the oral solution with low bio availability (A.T.10).