July 17 (UPI) -- Inhaled cannabis did not significantly reduce pain in hospitalized patients with sickle cell disease who also were treated with prescription opioid pain relievers, a study published Friday by JAMA Network Open found.
However, the drug did perform better than placebo and did reduce pain in the patients who received it, the researchers said.
"Inhaled cannabis appears to be safe when used in conjunction with opioids and better than placebo at reducing pain," study co-author Dr. Donald Abrams, an integrative medicine specialist at the University of California-San Francisco, told UPI.
However, "our study was small" -- 23 patients -- "and short" -- patients were evaluated over a five-day period -- "and statistical significance, which is the gold standard for medical and scientific research, was not achieved," he said.
Still, the drug performed well enough to suggest that larger studies in sickle cell disease and other pain-causing conditions are warranted, co-author Kalpna Gupta, a professor of hematology and oncology at the University of California, Irvine, told UPI.
Sickle cell disease is an inherited group of disorders that cause red blood cells to contort into a sickle shape, according to the Mayo Clinic. Affected cells die, causing a shortage of healthy red blood cells -- the condition called sickle cell anemia -- while dead cells can block blood flow causing pain, Abrams and Gupta said.
People with sickle cell disease experience chronic pain as well as episodes of acute or severe pain, they said.
Less than 200,000 people are diagnosed with the condition annually in the United States, according to the National Institutes of Health.
For their research, Abrams, Gupta and their colleagues treated 23 hospitalized sickle cell patients for pain with either an inhaled form of cannabis -- containing 4.4% tetrahydrocannbinol, or THC, and 4.9% cannabidiol -- or a placebo three times a day for five days.
Inhaled cannabis is delivered using a vaporizer, similar to an e-cigarette device or vape pen, they said.
The study compared participants who received inhaled cannabis to those given a placebo using the Visual Analog Scale. The method asks patients to rate their pain on a zero to 100 scale, with the higher number indicating worse pain, according to the researchers.
Compared to those on placebo, study participants who received the inhaled cannabis reported Visual Analog Scale scores that were five points lower on the first day, 11 points lower on the second day, 17 points lower on the third day, nine points lower on the fourth day and eight points lower on the fifth day, the researchers said.
Participants who received inhaled cannabis also did not report improved sleep, but did indicate improved mood, they said.
Vaporized cannabis may hold more promise for the treatment of pain than other forms of the drug because, unlike "oral and injected cannabinoids," it doesn't enter the bloodstream or "need to be processed by the liver," which can be problematic for patients with liver damage, Gupta said.