Over the past several years, the intensity of drug therapy has increased considerably. This increase is related, in part, to the introduction of new therapies, the recognition of the value of older therapies in new clinical settings and a greater reliance on drug therapy in patient management. Compounding the complexities of this clinically-based increase in activity is the gradual decrease in the average length of stay for hospitalized patients. More doses of drugs during a shorter length of stay create significant challenges to front-line caregivers under the best of circumstances. The increased use of diagnostic and interventional procedures requiring the patient to travel to other parts of the hospital adds to the challenge.
A interdisciplinary task force has been working for over a year redesigning the medication administration process. This process redesign is well under way and, when completed, should enable the hospital to better meet patient need and improve patient safety. The process redesign has involved Provider Order Entry, drug preparation and distribution and drug administration policies. A critical element in the process has been the standardization of the multitude of medication administration policies and practices present throughout the hospital, including standard medication administration times (SMAT). The task force also recognized that some guidance was necessary to deal with "missed doses" because of patient travel and unavailability on the care unit. Present policies did not address this problem, resulting in inconsistent resolution. Informal review of policies from other institutions show variation and do not appear to be based on pharmacokinetic principles.
The Drug Therapy Committee was asked for guidance on the problem of missed doses and administration of doses outside standard administration times. The Committee recommended what has come to be known as the "50% Rule". Simply put, the guidance suggests that a missed dose of drug should be administered as soon as the patient is available even if administered "late." Drugs may be administered under this guidance if the interval between the scheduled time of administration and the time of patient availability and subsequent drug administration is less than 50% of the scheduled dosing interval. Here are some examples of how this works in practice:
In both instances, had the patient unavailability extended beyond a period exceeding 50% of the dosing interval (after 8 PM in the first example or after 12 noon in the second) the guidance suggests that the dose be skipped and the next dose be administered at the scheduled time. The maximum effect on drug serum levels is dependent on the elimination half-life of the drug. In general, a slight drop in the serum level would be expected because of the "missed" dose being administered later than scheduled. However, this drop in serum level is offset by a slight increase in serum level after the next scheduled dose is administered. The impact of late administration is, as a result, negligible overall.
It is important to note that the "50% Rule" is only meant as a guide and not as an endorsement for missed doses of medication. The "50% Rule" is not intended as a replacement for professional judgement. The professional judgement of the physician, nurse and pharmacist caring for the patient takes precedence when clinically indicated.
By implementing standard medication administration times and using the 50% Rule to guide clinicians with medication administration practices, the task force hopes to establish standards by setting expectations when medications are to be administered and improve medication distribution by coordinating times when medications should be available to be given.
Thanks to Steven Haffa, RPh, for his comments on this manuscript.