Topic primers
A quick on-ramp for each area: the handful of facts that anchor it. Read one, then go practice. These are a launchpad, not a lecture.
PRIMER · Federal Requirements
Federal requirements, the essentials
- Schedule I has no accepted medical use; Schedules II to V step down in abuse potential.
- Schedule II prescriptions cannot be refilled; III and IV allow up to 5 refills within 6 months.
- DEA forms: 222 orders C-I/C-II stock, 106 reports theft or loss, 41 records destruction.
- An emergency oral Schedule II order needs a written follow-up within 7 days.
- Sublingual nitroglycerin is exempt from child-resistant packaging.
PRIMER · Order Entry & Processing
Order entry and calculations
- Quantity to dispense = dose x frequency x days (1 tab TID x 10 days = 30 tabs).
- Convert pounds to kilograms (lb / 2.2) before weight-based dosing.
- Percent w/v means grams per 100 mL (5% = 5 g per 100 mL).
- IV rate (mL/hr) = total volume / time; gtt/min = (volume x drop factor) / minutes.
- An NDC has three parts: labeler, product, package.
PRIMER · Medications
Medications, patterns first
- Class suffixes: -pril is an ACE inhibitor, -sartan an ARB, -olol a beta blocker, -statin a statin.
- ACE inhibitors classically cause a dry cough; ARBs do not.
- Warfarin is monitored by the INR (target usually 2 to 3).
- Metformin is held at the time of IV iodinated contrast in at-risk patients, then restarted 48 hours later if kidney function is stable.
- One generic can carry several brands (albuterol is ProAir, Ventolin, Proventil).
- Unopened insulin is refrigerated until it expires, never frozen.
PRIMER · Patient Safety & Quality Assurance
Patient safety essentials
- High-alert means severe harm if used in error (insulin, heparin, opioids, concentrated electrolytes).
- Tall-man lettering distinguishes look-alikes (DOPamine vs DOBUTamine).
- Do Not Use: write 'unit' not 'U', no trailing zero (5 mg), always a leading zero (0.5 mg).
- MedWatch Form 3500 is the voluntary report for health professionals and consumers; Form 3500A is the mandatory form used by manufacturers, distributors, and user facilities.
- A near miss is an error caught before it reaches the patient; a sentinel event is one that results in death, severe harm, or permanent harm.
PRIMER · Order Entry & Processing
Pharmacy calculations survival kit
- Days supply = total quantity / amount used per day; round down to whole days.
- Ratio strength 1:1000 = 1 g in 1000 mL = 1 mg/mL.
- Dilution: C1 x V1 = C2 x V2; solve for the unknown volume, then qs with diluent.
- Alligation parts: high-strength parts = desired - low; low-strength parts = high - desired.
PRIMER · Patient Safety & Quality Assurance
Hazardous drugs, hygiene, and dating opened products
- USP <800> is the standard for handling hazardous drugs (chemotherapy and others) from receipt through disposal; it protects workers, patients, and the environment.
- Hazardous drugs are handled with two pairs of chemotherapy-tested gloves, changed every 30 minutes or at once if torn or contaminated.
- A spill kit must be readily accessible wherever hazardous drugs are handled; a closed-system transfer device limits exposure when one is required.
- Hand hygiene is the single most important way to prevent contamination; clean counting trays and counters, and never eat or drink at the bench.
- An opened multiple-dose vial is good for 28 days unless the label says otherwise; a single-dose vial is used once and discarded. The earlier of the in-use date and the manufacturer's expiration date always wins.
PRIMER · Federal Requirements
Controlled substances at the counter
- A Schedule II may be phoned in only for a genuine emergency, with a written or electronic prescription to follow within 7 days.
- DEA Form 222 (or its electronic CSOS equivalent) is valid for 60 days from the date it is signed.
- DEA number check: add the 1st, 3rd and 5th digits, add twice the sum of the 2nd, 4th and 6th; the last digit of the total must equal the 7th digit.
- Watch for red flags: early refills, cash for large opioid quantities, prescribers far from the patient.
- A C-II may be partially filled at the patient's or prescriber's request (CARA, 2016); the remainder is due within 30 days of the issue date.
- Since 2023 an electronic C-II prescription may be transferred once between pharmacies, at the patient's request, for its initial fill.
PRIMER · Medications
Top drug classes cheat sheet
- ACE inhibitors (-pril) and ARBs (-sartan) lower blood pressure; both carry a boxed warning for fetal toxicity.
- Non-selective beta blockers (propranolol) can tighten airways; they are used cautiously in asthma and COPD.
- PPIs (-prazole) and H2 blockers (-tidine) reduce stomach acid.
- Benzodiazepines (-pam, -lam) are Schedule IV; SSRIs treat depression and anxiety.
- Opioids relieve pain and are controlled; watch for respiratory depression and constipation.
PRIMER · Order Entry & Processing
Insurance and billing basics
- A 'refill too soon' rejection means too much of the prior fill remains; wait for the plan's allowed date.
- DAW 0 = substitution allowed; DAW 1 = prescriber requires brand; DAW 2 = patient requests brand.
- A copay is a fixed amount per fill; a deductible is what the patient pays before coverage begins.
- Prior authorization requires the prescriber to justify a drug before the plan will cover it.
- AWP (Average Wholesale Price) is a common reimbursement benchmark (e.g., AWP minus a percent, plus a fee).
PRIMER · Patient Safety & Quality Assurance
Medication safety at a glance
- High-alert drugs (insulin, heparin, opioids, concentrated electrolytes) cause severe harm if misused; double-check them.
- Look-alike/sound-alike names use tall-man lettering to tell them apart (hydrALAZINE vs hydrOXYzine).
- Avoid error-prone abbreviations: U (write 'unit'), IU, QD/QOD, and MS; spell them out.
- Use a leading zero (0.5 mg) and no trailing zero (5 mg) to prevent 10-fold dosing errors.
- The rights of medication use: right patient, drug, dose, route, and time (plus documentation).
PRIMER · Order Entry & Processing
Reading a prescription
- Common sig codes: PO (by mouth), BID/TID/QID (2/3/4 times daily), PRN (as needed), HS (at bedtime), q6h (every 6 hours).
- Required elements: patient name, date, drug and strength, directions (sig), quantity, refills, and prescriber signature.
- Sig order: amount, route, frequency, timing ('1 tab PO TID PC' = one tablet by mouth three times daily after meals).
- AC = before meals, PC = after meals, stat = immediately.
- A controlled-substance prescription must also show the prescriber's DEA number and the patient's full name and address.
PRIMER · Medications
Interactions to flag for the pharmacist
- Grapefruit juice inhibits CYP3A4 and raises levels of drugs like simvastatin.
- Warfarin plus aspirin or NSAIDs raises bleeding risk; the pharmacist usually steers the patient to acetaminophen for occasional pain.
- ACE inhibitors or ARBs plus potassium supplements, salt substitutes, or potassium-sparing diuretics can push potassium dangerously high.
- Tetracyclines and fluoroquinolones cause photosensitivity; flag it so the pharmacist can counsel on sun protection.
- Doxycycline and levothyroxine absorption drops with calcium, iron, or antacids; separate the doses.