Drug use trends among Los Angeles County probationers over the last five years.

The frequency of use of various drugs including certain opiates, diazepam, barbiturates, amphetamines, methadone, cocaine, propoxyphene, methaqualone, and phencyclidine has been determined in Los Angeles County probationers during January and February of each of the last 5 years. The results indicate that while the overall amount of drug use has decreased slightly, the frequency of use of some drugs, such as phencyclidine and cocaine, has increased greatly while the frequency of use of most other drugs, such as phenobarbital and amphetamine, has considerably decreased.