The answer, according to a new study, is none.
The research by scientists at the University of New South Wales (UNSW) has been published in the journal Science.
The researchers, led by UNSW researcher, Dr. David Fagan, analyzed the therapeutic effects of various drugs and compared them with those of the most commonly used drugs, according the news release.
Fagan, along with Dr. Brian A. Koopman, a professor in the department of pharmacy at UNSW, analyzed drugs to determine their potency.
The study compared the therapeutic properties of a drug with the average potency of the available drugs.
The team used data from the Global Drug Survey, an ongoing survey of over 3,000 drugs across the globe, to examine the potency of various common drugs.
Frequency of use, dose, concentration and bioavailability were all taken into account to determine the potency.
According to the release, the team found the following:The average potency for some of the top 10 drugs tested was 4.2%, which is roughly equivalent to the strength of a common opioid.
The most potent of these drugs, OxyContin, was 4,904% stronger than the average.
It was also found that a common prescription painkiller was significantly more potent than other painkillers, and a generic version of it was almost as powerful.
The results were consistent with previous research by the same group, which found that the average strength of an opiate-based painkiller is approximately 2,500-4,000% stronger.
Drug companies have responded to the research by claiming that the researchers have mischaracterized their findings.