Drug Action and Shape of Molecules Several years ago two drug companies marketed a drug under the trade names Dexedrine and Benzedrine. The structure of the drug is shown below. H T -CH-C-CH NH The physical properties (C, H, and N analysis, melting point, solubility, etc.) of Dexedrine and Benzedrine were identical. The recommended oral dosage of Dexedrine (which is still available) was 5 mg/day, but the recommended dosage of Benzedrine (no longer available) was twice that. Apparently, it required considerably more Benzedrine than Dexedrine to yield the same physiologi- cal response. Explain this apparent contradiction.