Opioids Compatible With Most Adjuvant Agents in Solution

HOUSTON--Opioid solutions appear to be physically compatible witha number of adjuvant agents used in supportive care, researchersfrom M.D. Anderson Cancer Center report. They evaluated the physicalcompatibility of four injectable opioids--fentanyl, hydro-morphone,methadone, and morphine--with 14 drugs used for pain and symptommanagement (see table) for 48 hours.

Data on compatibility of opioids and adjuvant drugs have beenlacking, and the studies that are available tested compatibilityfor only 1 to 4 hours, says Sonja W. Chandler, PharmD, of theDivision of Pharmacy. Yet, for patients with multiple cancer symptoms,the ability to combine drugs in a single medication containercould improve the efficiency of drug delivery, reducing hospitaldrug preparation costs and limiting the need for frequent venousaccess.

A 5-mL sample of each opioid dilution was combined with a 5-mLsample of each of the supportive care drug solutions individuallyin colorless culture tubes. Each combination was prepared twiceso that the order of mixing for each two agents could be reversed.

Samples were examined visually immediately and at 1, 4, 24, and48 hours. Those samples that appeared clear were further examinedwith a high-intensity directional light source.

Since some drug products appear hazy by nature, samples were alsoevaluated with a turbidimeter, which allows measurement of thehaze and assessment of any changes. "A decrease in the expectedhaze may also be evidence of a physical incompatibility,"Dr. Chandler said. Samples with evidence of suspected incompatibilitywere further evaluated by a HIAC-Royce particle sizer and counter.

The results showed that all four opioid solutions appeared tobe compatible for at least 48 hours with all of the supportivecare drugs tested except pheny-toin sodium (J Pain Symptom Manage12:168-171, 1996).

Dr. Chandler and her colleagues, Lawrence Trissel, FASHP, andSharon Weinstein, MD, say that the results may aid the clinicianin treating the inpatient with limited venous access or the outpatientwith multiple treatment needs.

They cautioned, however, that the study represents an initialsafety screening only, and the results should be applied cautiouslyin the clinic.