Glossary
PTCB glossary
The words these questions assume you already know, in plain language. Each term lists the guides that teach it, and each guide links to the term where it first appears.
- beyond-use dateA beyond-use date is the last date a prepared or opened medication may be used. It is set by the pharmacy from USP standards, not by the manufacturer's expiration date on the stock bottle.
- BIDBID means twice a day, from the Latin bis in die. It is two doses in a day rather than a strict every-12-hours schedule — the fixed-interval order is written Q12H.
- days supplyDays supply is how long a dispensed quantity is meant to last: the quantity divided by the amount taken per day. It comes from the sig, not from the size of the package.
- DEA numberA DEA number is the nine-character registration identifier the DEA issues to a prescriber or a pharmacy: two letters, then seven digits. The second letter is the surname initial, and the last digit is a check digit.
- high-alert medicationA high-alert medication is one that bears a heightened risk of significant harm when it is used in error — insulin, heparin, opioids, concentrated electrolytes. The risk is the harm, not a higher error rate.
- national drug codeThe National Drug Code is the identifier a drug package carries in three segments — labeler, product, package. Labels print it as 10 digits in one of three layouts; billing systems key on an 11-digit padded form.
- NCC MERPNCC MERP publishes the Index for Categorizing Medication Errors, which sorts errors into categories A to I by outcome: A is a circumstance that could cause an error, B a near miss, and E to I harm.
- POPO means by mouth, from the Latin per os. It is the route written in the sig — 1 tab PO BID — and ISMP lists it as error-prone because the shorthand is not readable to every patient.
- PRNPRN means "as needed", from the Latin pro re nata. By itself it sets no schedule and no ceiling, so the sig must still state the dose, the shortest interval allowed, and the maximum in 24 hours.
- QDQD means once a day, from the Latin quaque die. It is on the Joint Commission's Do-Not-Use List because QD and QID are misread for each other, so the order is written out as "daily".
- QHSQHS means at bedtime, from the Latin hora somni — the hour of sleep. ISMP lists it as error-prone because HS also reads as "half strength", so the words are written out instead.
- QIDQID means four times a day, from the Latin quater in die. It is the abbreviation most often misread as QD, and one tablet four times a day is the classic fourfold-overdose signature.
- sig codeThe sig is a prescription's directions, and a sig code is the shorthand written inside it — BID for twice a day, QHS for at bedtime. The pharmacy expands each code into plain English on the label.
- tall man letteringTall man lettering puts capital letters into a drug name — glipiZIDE, glyBURIDE — so two look-alike names stop looking alike. FDA and ISMP each publish a list, and they are not the same list.
- therapeutic duplicationTherapeutic duplication is two drugs from the same therapeutic class — or the same drug under two names — on one patient profile at the same time. It is a routine DUR screening category.
- TIDTID means three times a day, from the Latin ter in die. It is three doses spread across the waking day, not a strict every-8-hours order — that one is written Q8H.