4.1 Prescription Interpretation

PTCE Pharmacy Technician Certification Exam

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1 Introduction

About the PTCE How to Use This Guide

2 Chapter 1: Medications

1.1 Generic and Brand Drug Names & Classifications 1.2 Cardiovascular and Anticoagulant Medications 1.3 Anti-Infective and Analgesic Medications 1.4 Endocrine, Respiratory, CNS, and Storage Requirements

3 Chapter 2: Federal Requirements

2.1 DEA Regulations and Controlled Substance Schedules 2.2 Drug Supply Chain Security Act (DSCSA) 2.3 FDA Regulations and Drug Recalls 2.4 HIPAA, CMEA, and Prescription Requirements

4 Chapter 3: Patient Safety and Quality Assurance

3.1 Medication Error Prevention 3.2 High-Alert and Look-Alike/Sound-Alike Medications 3.3 Patient Counseling and Communication 3.4 Quality Assurance and Continuous Quality Improvement

5 Chapter 4: Order Entry and Processing

4.1 Prescription Interpretation 4.2 Pharmacy Calculations 4.3 Inventory Management and NDC Numbers 4.4 Insurance, Billing, and Prescription Processing

4.1 Prescription Interpretation

Key Takeaways Explain This Topic AI

Sig codes are Latin-based abbreviations that communicate dosing instructions.

Common sig codes include BID (twice daily), TID (three times daily) and QID (four times daily); QD (daily) and QOD (every other day) are on The Joint Commission's "Do Not Use" list, so write "daily" and "every other day".

Route abbreviations specify how medication is administered: PO (by mouth), SL (sublingual), TOP (topical).

Prescriptions must contain prescriber info, patient info, drug name, strength, quantity, sig, refills, and date.

The DAW (Dispense As Written) code indicates whether generic substitution is permitted.

Last updated: November 2026

Quick Answer: Prescription interpretation involves reading and understanding all elements of a prescription including sig codes (dosing instructions), drug names, quantities, and prescriber directives. Mastery of common abbreviations like QD (daily), BID (twice daily), and PO (by mouth) is essential for accurate dispensing.

Pharmacy technicians must accurately interpret prescriptions to ensure patients receive the correct medication with proper instructions. This section covers the essential abbreviations, sig codes, and prescription elements you need to know.

Required Prescription Elements

Every valid prescription must contain:

• Element Description Example
• Prescriber Information Name, address, phone, DEA# (for controlled substances) Dr. Smith, 123 Medical Way
• Patient Information Full name, date of birth, address John Doe, DOB 01/15/1980
• Date Written Date prescription was issued 01/21/2026
• Drug Name Brand or generic name Lisinopril
• Drug Strength Dosage strength per unit 10 mg
• Quantity Amount to dispense #30 (thirty)
• Sig (Directions) Instructions for patient 1 tab PO QD
• Refills Number of refills authorized Refills: 5
• Prescriber Signature Handwritten or electronic signature [Signature]
• Common Sig Codes (Frequency)

• Abbreviation Latin Origin Meaning
• QD or QDay Quaque die Once daily
• BID Bis in die Twice daily
• TID Ter in die Three times daily
• QID Quater in die Four times daily
• Q4H Quaque 4 hora Every 4 hours
• Q6H Quaque 6 hora Every 6 hours
• Q8H Quaque 8 hora Every 8 hours
• Q12H Quaque 12 hora Every 12 hours
• QHS Quaque hora somni At bedtime
• QAM Quaque ante meridiem Every morning
• QPM Quaque post meridiem Every evening
• PRN Pro re nata As needed
• AC Ante cibum Before meals
• PC Post cibum After meals
• STAT Statim Immediately
• QOD Quaque altera die Every other day
• QWK Quaque week Once weekly

Safety Note: QD (once daily) and QOD (every other day) are on ISMP's list of error-prone abbreviations and on The Joint Commission's minimum "Do Not Use" list: QD can be mistaken for QID, and QOD for QD or QID. Write "daily" and "every other day" instead.

Route of Administration Abbreviations

• Abbreviation Meaning
• PO By mouth (per os)
• SL Sublingual (under the tongue)
• TOP or EXT Topically (on the skin)
• IM Intramuscular injection
• IV Intravenous injection
• SC or SQ or SubQ Subcutaneous injection
• PR Per rectum
• PV Per vagina
• INH Inhalation
• OU Both eyes
• OD Right eye
• OS Left eye
• AU Both ears
• AD Right ear
• AS Left ear
• NAS Nasal
• GT Gastrostomy tube
• NGT Nasogastric tube
• Form Abbreviations

• Abbreviation Meaning
• TAB Tablet
• CAP Capsule
• SOL Solution
• SUSP Suspension
• SUPP Suppository
• INJ Injection
• GTT Drops
• UNG Ointment
• CR/CRM Cream
• LOT Lotion
• SYR Syrup
• ELIX Elixir
• MDI Metered-dose inhaler
• EC Enteric-coated
• ER/XR/LA/SR Extended/sustained release
• DAW Codes (Dispense As Written)

DAW codes indicate whether generic substitution is allowed:

• DAW Code Meaning
• 0 No product selection indicated (generic substitution permitted)
• 1 Substitution not allowed by prescriber
• 2 Substitution allowed - patient requested brand
• 3 Substitution allowed - pharmacist selected brand
• 4 Substitution allowed - generic not in stock
• 5 Substitution allowed - brand dispensed as generic
• 6 Override
• 7 Substitution not allowed - brand mandated by law
• 8 Substitution allowed - generic not available
• 9 Other
• Reading a Complete Sig
• Example Prescription Sig: Lisinopril 10mg #30 Sig: i tab PO QD

Interpretation:

• i tab = 1 tablet (Roman numeral i = 1)
• PO = by mouth
• QD = once daily
• Translation: "Take one tablet by mouth once daily"
• Example 2: Amoxicillin 500mg #21 Sig: i cap PO TID x 7 days

Interpretation:

• i cap = 1 capsule
• PO = by mouth
• TID = three times daily
• x 7 days = for 7 days
• Translation: "Take one capsule by mouth three times daily for 7 days"