Cost considerations of analgesic therapy: an analysis of the effects of dosing frequency and route of administration.

Using work sampling methodologies, we compared both acquisition and administration costs of equivalent daily doses of controlled-release morphine tablets and morphine sulphate solution. A total cost for each drug therapy was derived by summing: (i) the acquisition cost of the medication, (ii) the cost of drug administration supplies, (iii) the cost of pharmacy time required for packaging and distribution of doses to nursing units, (iv) the cost of nursing time required to administer the medication, (v) the cost of nursing time required to complete the requisite narcotic records. Acquisition costs for controlled-release morphine tablets, morphine sulphate solution and ancillary materials required for dosing were those actually paid by the hospital pharmacy at the time of the study. Costs for nursing and pharmacy time for administration of doses were based on our analysis of the time required to perform each step of the procedure and the median hourly wage for the corresponding position from the British Columbia collective agreement. Assuming a mean total daily morphine dose of 120 mg, administered as one 60 mg controlled-release morphine tablet 12 hourly or 20 mg (4 ml of 5 mg/ml) morphine sulphate solution 4 hourly, morphine solution had a lower acquisition cost than controlled-release tablets ($0.48 vs. $2.32 per day; respectively). However, the saving in acquisition costs was offset by a higher administration cost ($10.20 vs. $2.86 per day). These figures indicate that administration of 120 mg morphine per day to hospitalized patients for 30 days would have a total cost of $155.40 using a regimen to 60 mg controlled-release morphine 12 hourly. In contrast, total cost for a 30 day regimen of 20 mg morphine solution 4 hourly would be $320.40. Thus, an analysis which considers both acquisition and administration costs reveals that the frequency of administration is an important factor in the overall cost of drug therapy and that controlled-release formulations may ultimately be less costly to administer than their immediate release counterparts. A separate analysis of costs associated with the administration of morphine by continuous subcutaneous infusion demonstrated that providing analgesia by this route was significantly more costly than via the oral route.