HOUSTON--Opioid solutions appear to be physically compatible with a number of adjuvant agents used in supportive care, researchers from M.D. Anderson Cancer Center report. They evaluated the physical compatibility of four injectable opioids--fentanyl, hydro-morphone, methadone(Drug information on methadone), and morphine(Drug information on morphine)--with 14 drugs used for pain and symptom management (see table) for 48 hours.
Data on compatibility of opioids and adjuvant drugs have been lacking, and the studies that are available tested compatibility for only 1 to 4 hours, says Sonja W. Chandler, PharmD, of the Division of Pharmacy. Yet, for patients with multiple cancer symptoms, the ability to combine drugs in a single medication container could improve the efficiency of drug delivery, reducing hospital drug preparation costs and limiting the need for frequent venous access.
A 5-mL sample of each opioid dilution was combined with a 5-mL sample of each of the supportive care drug solutions individually in colorless culture tubes. Each combination was prepared twice so that the order of mixing for each two agents could be reversed.
Samples were examined visually immediately and at 1, 4, 24, and 48 hours. Those samples that appeared clear were further examined with a high-intensity directional light source.
Since some drug products appear hazy by nature, samples were also evaluated with a turbidimeter, which allows measurement of the haze and assessment of any changes. "A decrease in the expected haze may also be evidence of a physical incompatibility," Dr. Chandler said. Samples with evidence of suspected incompatibility were further evaluated by a HIAC-Royce particle sizer and counter.
The results showed that all four opioid solutions appeared to be compatible for at least 48 hours with all of the supportive care drugs tested except pheny-toin sodium (J Pain Symptom Manage 12:168-171, 1996).
Dr. Chandler and her colleagues, Lawrence Trissel, FASHP, and Sharon Weinstein, MD, say that the results may aid the clinician in treating the inpatient with limited venous access or the outpatient with multiple treatment needs.