"Mother's Little Helper" is 25 years old this month, and drug-abuse treatment experts say that the tranquilizer memorialized in song by the Rolling Stones, unfortunately, is keeping up with the times.

The nationwide epidemic of cocaine addiction has propelled prescription tranquilizers like Valium into a new era of abuse, when large quantities are consumed to cushion the "crash" from an illicit high, these experts say.Increasingly, benzodiazepine tranquilizers are turning up as street drugs, addicting a new group of people who are already chronic cocaine users, said Dr. Stanley Yan-covitz, Chief of the Division of Chemical Dependency at New York's Beth Israel Medical Center.

"It's escalating with the cocaine epidemic, particularly with the more potent form of cocaine people use," he said, referring to the smokable form called "crack."

"Cocaine is accelerating addictions to some of the hypnotics. It's kind of pathetic to see someone who starts out snorting cocaine and ends up, in the extreme case, shooting heroin," he said.

Tranquilizers follow alcohol as the leading secondary addiction with cocaine, he added.

Introduced 25 years ago as an antidote for anxiety, Valium soon was considered America's most over-prescribed drug and was even the subject of a popular rock song. Last year, it was overtaken by Xanax as the most prescribed in its class.

A new survey from San Francisco's Haight-Ashbury Free Clinic indicates a sharp upswing in cocaine use that is combined with the use of benzodiazepines like Valium, Xanax and Halcion.

Dr. David Smith, the director and founder of the community-based clinic, said the combination reflects the growing pattern of polydrug abuse and is similar to one that was dangerously common in the 1960s, with one addiction fueling the other.

"The focus is basically uppers and downers," he said in a telephone interview prior to releasing his report Nov. 17.

"The primary drug for going up now is cocaine. When people abuse cocaine, they become paranoid and anxious and use depressants to come down. At my own clinic, I have seen a big increase in use of cocaine as an upper and benzodiazepines or alcohol as a downer, duplicating a situation that was seen in the '60s, that was very, very serious."

While considerable attention has been focused on the overprescribing of benzodiazepines, Smith said prescriptions, in fact, have been leveling off, while street use has been growing.

"This is a new level of abuse," he said, noting that the extremely high dosages used to counteract cocaine-related jitters can have severe behavioral, if not physiological, affects.

The upper-downer cycle is both "seductive" and "destructive," Smith said.

"A cocaine toxic person can tolerate enormous doses of benzodiazepines, which can produce major impairment of judgement," his report said.

"Combining the high energy levels produced by a stimulant with the added impairment of judgement induced by large doses of sedatives can result in unpredictable, dangerous and socially disruptive behavior."

Yancovitz noted that cocaine has complicated the needs of people seeking treatment for drug abuse problems.

"The average admission at treatment centers is currently someone under 50 years old who is abusing a minimum of two substances. Ten years ago, the average admission was abusing just one substance. So cocaine has shifted the average."

Smith said physicians should be alert to patients requesting tranquilizer prescriptions for what really may be symptoms of cocaine addiction.

The survey, performed in cooperation with the Merritt Peralta Chemical Dependency Recovery Hospital in Oakland, reached 339 inpatient and outpatient drug treatment programs around the country.

The respondents overwhelmingly agreed that cocaine use was increasing.