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TL;DR

Sig Codes (Prescription Abbreviations): Latin-based abbreviations: PO (by mouth), BID (twice daily), QHS (at bedtime), PRN (as needed), QID (four times daily).

By Valenke Exam Prep Team·Last updated 2026-06-02

Sig Codes (Prescription Abbreviations)

PTCB

Definition

Latin-based abbreviations: PO (by mouth), BID (twice daily), QHS (at bedtime), PRN (as needed), QID (four times daily).

Patient Communication

Clear communication about sig codes (prescription abbreviations) with patients, families, and the healthcare team is essential. Use standardized handoff tools (SBAR) for shift changes and transfers. Verify understanding by asking the patient to repeat key information back to you.

Assessment Techniques

Latin-based abbreviations: PO (by mouth), BID (twice daily), QHS (at bedtime), PRN (as needed), QID (four times daily). Sig code interpretation and days supply calculation extensively tested on PTCB exam.

Related drug class: Fluoroquinolones includes ciprofloxacin, levofloxacin, moxifloxacin. Mechanism: Inhibit bacterial DNA gyrase and topoisomerase IV, bactericidal.

Exam Focus Areas

On the Ptcb exam(s), questions about sig codes (prescription abbreviations) typically test:

  1. Drug interactions and contraindications that affect patient safety
  2. Federal and state regulations governing practice
  3. Mathematical calculations: dosage, days supply, dilutions, and compounding
  4. Drug classification, mechanism of action, and common side effects

Overview

Latin-based abbreviations: PO (by mouth), BID (twice daily), QHS (at bedtime), PRN (as needed), QID (four times daily). Sig code interpretation and days supply calculation extensively tested on PTCB exam.

Related drug class: Fluoroquinolones includes ciprofloxacin, levofloxacin, moxifloxacin. Mechanism: Inhibit bacterial DNA gyrase and topoisomerase IV, bactericidal.

Regulatory Context

Regulatory framework for sig codes (prescription abbreviations) in pharmacy:

Schedule I
No accepted medical use, high abuse potential. Examples: heroin, LSD, peyote, ecstasy, marijuana (federal). Storage: Not dispensed in pharmacies
Schedule III
Moderate abuse potential. Examples: testosterone, ketamine, Tylenol with codeine. Storage: 5 refills in 6 months, written/oral/electronic Rx
Schedule II
High abuse potential with accepted medical use. Examples: oxycodone, fentanyl, morphine, amphetamine, methylphenidate. Storage: Double-locked, perpetual inventory, no refills, written/electronic Rx only

Why It Matters

Sig code interpretation and days supply calculation extensively tested on PTCB exam.

Related Terms

Pharmacy CalculationsDosage Forms

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Frequently Asked Questions

What sig codes are commonly seen with sig codes (prescription abbreviations) prescriptions?▼
For sig codes (prescription abbreviations): PC = after meals, AC = before meals, QD = once daily, SL = sublingual, QHS = at bedtime.
What drug interactions should be monitored for sig codes (prescription abbreviations)?▼
For sig codes (prescription abbreviations): ACE inhibitors (lisinopril, enalapril, ramipril): Dry cough (10-15%); Hyperkalemia; Angioedema (rare but serious); Teratogenic: contraindicated in pregnancy. Always check for drug interactions before dispensing.
What calculations are involved in sig codes (prescription abbreviations)?▼
For sig codes (prescription abbreviations): body weight dosing: dose (mg/kg) * weight (kg) = total dose. Example: Vancomycin 15mg/kg * 80kg = 1200mg.