Order Entry and Processing
Core concepts
Order entry requires accurate interpretation of the prescription: patient identifiers, drug, strength, dosage form, quantity, directions (sig), refills, prescriber, and date. Master sig abbreviations (po, prn, qd, bid, tid, qid, q4h, ac, pc, hs), metric conversions, ratio/proportion and dimensional analysis, and days-supply calculations. Understand DAW codes, generic substitution, prior authorization, refill-too-soon and quantity-limit rejects, and how to calculate quantity from a sig. In processing, verify DEA number validity, ensure leading zeros are used and trailing zeros are avoided, and document interventions.
Traps
Look-alike abbreviations cause errors: qd vs qid, MS vs MSO4, U for units. A sig may say “2 tabs po bid x 10 days”; the quantity is 2 × 2 × 10 = 40 tablets. Do not bill the package size when the prescribed quantity differs. For PRN directions, days supply may require a maximum-use assumption per policy. Also separate quantity dispensed from days supply and refills remaining.
Worked example
Sig: “Take 1 tablet by mouth twice daily for 10 days.” Quantity = 1 × 2 × 10 = 20 tablets. If the pharmacy stocks 30-count bottles, dispense 20, not 30, unless the prescription or payer rules require a full package and the quantity is adjusted appropriately.
Rule of thumb
Write 0.5 mg, never .5 mg; write 5 mg, never 5.0 mg. Convert the sig to a calculation before entering it.