Potential savings from generic prescribing and generic substitution in South Africa.

Generic prescribing and generic substitution are mechanisms for reducing the cost of drugs. The purpose of this study was to assess the extent to which generic prescribing by private medical practitioners and generic substitution by private pharmacists is practised in South Africa and to estimate the potential savings from these two practices. Prescriptions from 10 pharmacists were collected on four randomly selected days. Computer printouts of all the prescriptions dispensed on these four days together with the original doctor's prescription were priced using a commercially available pharmacy dispensing computer package. A total of 1570 prescriptions with a total number of 4086 items were reviewed. Of the total prescriptions, 45.7% had at least one item for which there was a generic equivalent. Of the 961 drugs which had generic equivalents, 202 (21 %) were prescribed using the generic name of the drug. Only 0.3% of prescribers prohibited generic substitution. The cost of the prescription as dispensed was 1.4% (mean cost: R116.19 vs R117.84) below that of the original doctor's prescriptions, indicating the marginal benefit from the current low substitution rate of 13.9% by pharmacists. About 6.8% of the cost of the original doctor's prescriptions (mean cost: R117.84) could have been saved if total generic substitution (mean cost: R109.65) was practised. The cost of the prescriptions with only brand name items (mean cost: R120.49) would have been 9.9% higher than if generic drugs were used. Current restrictive prescribing and dispensing practices result in marginal cost savings from generic prescribing and generic substitution. Both these practices have a potential to reduce drug costs, if actively encouraged and practised to maximum capacity. It is noteworthy, however, that the potential savings from generic prescribing and substitution are at most 9.9% in the absence of any changes in types of drugs prescribed.

Novel nucleoside inhibitors of guanosine metabolism as antitumor agents.

A detailed study of the inhibition of DR and TR in the SkLu-1 line of human lung adenocarcinoma has shown that TR significantly inhibits this tumor line, probably via inhibition of IMP dehydrogenase by the corresponding TAD analog of NAD. DR exhibited a similar degree of inhibition in this cell line. In a system devised to detect the inhibition of cloning efficiency of the SkLu cells, DR showed a 50% inhibition at 4 X 10(-3) M and TR at 1 X 10(-4) M. When DR and TR were used in combination, the ID50 was decreased to 3 X 10(-5) M. The study of DR in a number of human carcinoma cell lines revealed that de novo purine biosynthesis was significantly inhibited; however, in the SkLu-1 lung carcinoma cells this inhibition was not observed. The synergism observed in this cell line is presently viewed as potentially due to both agents acting on IMP dehydrogenase at different sites.