BACKGROUND: Jet injection eliminates the risk of contaminated needlestick injuries when giving intramuscular or subcutaneous medications. Clinical efficacy of the Biojector System was equivalent to that of needle and syringe injection in unpublished trials with vaccines, but had not been studied using other drugs. OBJECTIVE: To compare the effectiveness of the Biojector with conventional needle and syringe injection in administering intramuscular morphine and subcutaneous heparin to healthy adults, as measured by plasma drug concentration. METHODS: Intramuscular injections of morphine 8 mg (5 mg if weight < or = 65 kg) were given 24 hours apart with the jet injector and with a needle and syringe to 30 subjects at the deltoid site and 10 subjects at the dorsogluteal site. Blood samples for plasma concentrations of free morphine were drawn at 15, 30, 45, 60, 120, and 240 minutes and were analyzed using radioimmunoassay. Abdominal subcutaneous injections of heparin 3500 U were given every 8 hours for 5 days with both injection methods to 29 subjects, with 48 hours between the two series. Daily blood samples for plasma heparin were analyzed by colorimetric assay for antifactor Xa activity. RESULTS: Mean free morphine concentration, peak value, and area under the curve did not differ significantly between the deltoid and dorsogluteal sites or between the jet injector and needle and syringe. Values of mean daily heparin concentrations and area under the curve were low and did not differ between the two injection methods. CONCLUSION: Plasma drug concentrations provided by the Biojector were equivalent to those provided by conventional needle and syringe when administering intramuscular morphine and low-dose subcutaneous heparin.

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