Which drug is noted for having increased THC potency since the early 1960s?

Marijuana is noted for having increased THC potency since the early 1960s due to advancements in cultivation techniques, selective breeding, and more sophisticated growing methods. As a result, marijuana strains available today typically contain significantly higher concentrations of tetrahydrocannabinol (THC), the principal psychoactive component in cannabis.

During the early 1960s, the average THC content in marijuana was relatively low, often below 2%. However, recent years have seen strains with THC levels exceeding 30% in some cases, making marijuana considerably more potent than it was five decades ago. This increase in potency has implications for both recreational and medicinal use, affecting dosage, effects, and potential risks associated with use.

The other substances listed, while they may have fluctuations in their availability, purity, or formulation over the years, do not exhibit the same trend of significantly increased potency related to a specific active compound like THC in marijuana.