Intro to Pharmacy Concepts - Comprehensive Notes

Unit Overview

  • Unit Overview
  • Patient Interviewing
  • Skills Lab
  • Lab Value Documentation
  • Prescriptions & Calculations
  • Intro to Therapeutics
  • Collecting Information & Documentation (EHRGo & SOAP Notes)
  • Today: Foundational Knowledge (drug targets, ADME)
  • Tomorrow: Application Activity 2

Prescription Learning Objectives

  • List the steps in the medication use process. (173, 198)
  • Differentiate between prescription/legend and over-the-counter (OTC) medications. (173)
  • Differentiate between generic and brand/trade names of medications. (173)
  • Describe the components of a medication order (e.g., prescription). (173, 175)
  • Define basic prescription terminology including dose, strength, concentration, route, frequency, duration, sig, instructions, and quantity. (12, 13, 173)
  • Differentiate between a medication titration and medication taper. (29)
  • Define total daily dose. (29)
  • Calculate days’ supply for a provided medication order. (181)
  • Distinguish among the types of dosing (initial dose, dose titration, and maximum dose). (29)

Medication Use Process & Pharmacy Systems

  • Medication Use Process (flow from prescribing to monitoring)
  • Billing System/Claims Adjudication
  • Electronic Medical Record (EMR)
  • Electronic Medication Administration Record (eMAR)
  • Patient Assessment
  • Barcode Medication Administration
  • Clinical Decision Support (CDS)
  • Administration
  • Medication Administration
  • Intelligent Infusion Pumps
  • Medication Order
  • e-Prescribing
  • Pumps
  • Automated Dispensing Cabinets (ADCs)
  • Cart Fill Robotics
  • Medication Dispensing
  • Pharmacist Evaluation
  • Computerized Provider Order Entry (CPOE)
  • Pharmacy Information System / Packagers System
  • Prescription transcription/documenting
  • Prescribing → Transcribing/Documenting → Dispensing → Administering → Monitoring

Rx vs OTC Meds

  • Prescription medications = Legend drugs
  • By law, can only be obtained with a prescription
  • Federal law: “Caution: Federal law prohibits dispensing without a prescription”
  • Schedule drugs = Medications with high abuse/dependence potential
  • Over-the-counter (OTC) medications = Nonprescription medications
  • Bought off-the-shelf in stores
  • Do not require a prescription

Brand vs Generic Medications

  • No difference in active ingredients or strength/dosage between brand and generic
  • Brand medications
    • Higher in cost
    • Insurance may cover if no generic form exists
    • Packaging/appearance often standardized (includes ® or ™ symbol)
  • Generic medications
    • Lower in cost
    • Usually always covered by insurance
    • Packaging and appearance may differ from brand

Prescriptions vs. Medication Orders

  • Prescription Drug Order (Rx) = A lawful order of a licensed practitioner for a medication, device, or pharmaceutical care for a specific patient

Prescriptions vs. Medication Orders (Continued)

  • “Scripts”
  • Used in outpatient care
  • Pre = before; Script = writing, written
  • Used in hospital and institutional care settings
  • May also contain directions for procedures, lab tests, discharge instructions

Rx Components (1–4)

  1. Prescriber Identification: name, license designation, address, DEA number (controlled drugs)
  2. Patient Identification: full name, age/DOB, street address
  3. Date prescription was written
  4. Superscription (Rx): “take thou”, “you take”, “recipe” (if compounded)
  5. Signature of prescribing practitioner

Rx Components (5–8)

  1. Inscription: the medication prescribed including name, strength, dosage form
  2. Subscription: dispensing instructions to pharmacist including quantity to dispense (#tabs, volume of liquid)
  3. Signa (Sig): directions for use; pharmacist must transcribe for patient on label
  4. Special labeling & instructions: refills, generic product substitution

Terminology

  • Drug = Active pharmaceutical ingredient
  • Strength = Amount of drug (active ingredient) in one unit
    • e.g., 500 mg tablet, syringe containing 80 mg
  • Concentration = The amount of drug (active ingredient) in a specific volume
    • e.g., suspension containing 5 mg per mL
  • Drug Product = Active + inactive ingredients (includes dosage form and strength or concentration)
    • e.g., metformin 500 mg tablet, ibuprofen suspension 100 mg / 5 mL

Terminology (Dose, Route, Frequency, Duration)

  • Dose = Amount of drug taken at one time (unless specified as “total daily dose”)
    • e.g., 500 mg tablet; take 2 tablets [dose = 1000 mg]
    • e.g., 5 mg/mL suspension; take 5 mL [dose = 5 mL or 25 mg]
  • Route = How administered
    • e.g., by mouth (oral), intravenous (IV), subcutaneous (SC), intramuscular (IM), sublingual (SL), rectal
  • Frequency = How often
    • e.g., daily, twice per day, as needed
  • Duration = How long the drug is to be taken
    • e.g., antibiotics x 10 days; sometimes determined by days’ supply

Terminology (Sig, Instructions, Quantity, Days’ Supply)

  • Sig (Signa) = Directions supplied by the prescriber to the pharmacist for interpretation
    • Should include information on dose, route, and frequency
    • e.g., Take 2 tablets by mouth BID
  • Instructions = Directions the pharmacy places on the product for the patient
    • e.g., Take 2 tablets by mouth twice a day; Take 1 capsule as needed for pain
  • Quantity = Total amount dispensed to the patient; may be in tablets, units, mL, etc.
    • Dose does NOT include the amount provided by a refills
  • Days’ Supply = Number of total/complete days the amount dispensed will last
    • Based on amount needed per dose, frequency, and duration
    • This is NOT the supply/amount to be taken per day

Dosing Information

  • Total Daily Dose (TDD) = The amount of medication a patient takes every day
    • Example: carvedilol 25 mg twice daily
    • extTDD=25 mg/dose×2 doses/day=50 mg/dayext{TDD} = 25\text{ mg/dose} \times 2\text{ doses/day} = 50\text{ mg/day}
  • Medication titration = Slowly increasing the dose of a medication by small amounts over days, weeks, or months to find an effective dose
  • Medication taper = Gradually decreasing the total daily dose of a medication
    • Typically, the goal is discontinuing the medication
  • Example: Lisinopril (Prinivil)
    • Initial dose: 5–10 mg once daily
    • Dose titration: increase daily dose by doubling every 2–4 weeks as needed
    • Maximum dose: 40 mg once daily

Let’s Practice…

  • Task: List the strength, dose, route, frequency, duration, days supply, and total daily dose
  • Activity: As a team, enter responses on Padlet under each prescription header: https://padlet.com/kleppel/practice-interpreting-prescriptions-safk8jjf65cm865a

Abbreviations Learning Objectives

  • List the common units and abbreviations of dosing and conversions. (12, 66)
  • Define standard abbreviations for medication routes. (12)
  • Match abbreviation with route terminology. (30)
  • Define standard abbreviations for medication frequency. (12)
  • Match abbreviation with frequency terminology. (31)

Medical Abbreviations

  • Use common/standard abbreviations
  • See Medical Abbreviations resource document
  • Never “create” abbreviations
  • Never try to interpret prescribers’ shorthand abbreviations
  • Ask for clarification from writer if uncertain of meaning
  • Avoid abbreviations that lead to errors
  • See ISMP Error-Prone Abbreviations, Symbols, and Dose Designations document

Abbreviation Examples

  • Routes of Administration
    • PO = by mouth
    • SL = Sublingual
    • IV = Intravenous
    • IM = Intramuscular
    • SQ = Subcutaneous
    • PR = Rectal or per rectum
    • Right ear (AD) – Left ear (AS)
    • Both ears (AU)
    • Right eye (OD) – Left eye (OS)
    • Both eyes (OU)
  • Medication Frequency Abbreviations
    • Daily (QD)
    • Every morning (QAM)
    • Twice daily (BID)
    • Three times daily (TID)
    • Four times daily (QID)
    • Every other day (QOD)
    • Every 4 hours (Q4h)
    • At bedtime (HS or QHS)
    • Before meals (AC)
    • After meals (PC)
    • Discontinue (D/C)
    • As needed (PRN)

Calculations Learning Objectives

  • Conduct basic calculations using order of operations and basic algebra. (66, 181)
  • Review basics of rounding (whole numbers, tenths, hundredths, etc.). (66, 181)
  • Review metric & US customary unit conversions. (66, 181)
  • Calculate unit conversions. (66, 181)
  • Interpret word problems to identify pertinent information. (4)

Pharmacy Calculations

  • Calculate doses of medications
  • Quantities of pharmaceutical ingredients for compounding
  • Dose adjustments for disease state management
  • IV fluid rates & drip rates
  • Days’ supply & number of units to dispense
  • See the Pharmacy Calculations Primer document for review of:
    • Basic Order of Operations (PEMDAS)
    • Metric & US Customary Units
    • Rounding Basics for Pharmacy
    • Pharmacy Calculations Basics
    • Proportions
    • Dimensional Analysis

Practice Problems and Solutions

  • Practice Problem #1: A set of AA batteries lasts 3 hours and 30 min in a radio under constant use. How many hours will the radio play on 14 sets of batteries?
    • Solution: Each set lasts 3.5 hours. Total = 3.5 hours × 14 = 49 hours
  • Practice Problem #2: Recipe brownie math. 2 1/2 cups of cocoa for 4 people. How many cups for 38 people?
    • Solution: 2.5 × (38/4) = 2.5 × 9.5 = 23.75 cups (23 3/4 cups)
  • Practice Problem #3: Ocuflox contains 0.3% w/v (0.3 g per 100 mL) of ofloxacin. How many mL needed to deliver 0.15 mg of ofloxacin?
    • Solution: 0.3 g/100 mL = 0.003 g/mL = 3 mg/mL
    • Volume = 0.15 mg ÷ 3 mg/mL = 0.05 mL
  • Practice Problem #4: Nutr-E-Sol contains 400 IU per tablespoon of vitamin E. Dose = 45 drops. Dropper = 15 drops/mL. How many IU for 45 drops?
    • 45 drops = 3 mL; 1 mL contains 400/15 ≈ 26.67 IU
    • Total IU ≈ 26.67 × 3 ≈ 80 IU
  • Practice Problem #5: Carvedilol 6.25 mg tablets. Take one tablet twice daily. What is the total daily dose (TDD) in mg and tablets? How many tablets for a 90-day supply?
    • TDD = 6.25 mg × 2 = 12.5 mg/day; equals 2 tablets/day
    • 90 days: 2 tablets/day × 90 days = 180 tablets
  • Practice Problem #6: 250 mL bag of D5W contains 5 mg of a drug. Flow rate = 2.5 mcg/min. IV pump delivers in mL/min; what is the rate in mL/h?
    • Concentration: 5 mg/250 mL = 0.02 mg/mL = 20 mcg/mL
    • Rate (mL/min): 2.5 mcg/min ÷ 20 mcg/mL = 0.125 mL/min
    • Rate (mL/h): 0.125 × 60 = 7.5 mL/h
  • Practice Problem #7: Moving van rental: $30 per day + $0.50 per mile. Rented for 2 days and total cost = $360. How many miles were driven?
    • Cost: 2×$30 + $0.50×M = $360 -> 60 + 0.5M = 360 -> 0.5M = 300 -> M = 600 miles

Coming Up

  • Introduction to Therapeutics
  • Thinking like a pharmacist
  • Drug interactions
  • Things you should know & practice…
  • Practice interpreting SIGs
  • Calculate total daily dose (TDD) and days supply
  • Convert between metric and US customary units
  • Practice with word problems