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TL;DR

Therapeutic Equivalence: FDA Orange Book determination that a generic is bioequivalent and substitutable for the brand.

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

Therapeutic Equivalence

PTCB

Definition

FDA Orange Book determination that a generic is bioequivalent and substitutable for the brand.

Practical Example

Pharmacy Calculation Example: dilution

Formula: C1V1 = C2V2

Worked example: Dilute 70% alcohol to 30%: (70)(V1) = (30)(500mL), V1 = 214.3 mL

Common Errors

Frequent errors with therapeutic equivalence in pharmacy practice:

  1. Misreading sig codes. For reference: OU = both eyes; OD = right eye; QID = four times daily; PO = by mouth; QHS = at bedtime; OS = left eye
  2. Calculation errors in dosage. Always double-check units (mg vs mcg, mL vs L)
  3. Wrong DEA schedule classification affecting storage and dispensing requirements

Exam Focus Areas

On the Ptcb exam(s), questions about therapeutic equivalence typically test:

  1. Mathematical calculations: dosage, days supply, dilutions, and compounding
  2. Drug classification, mechanism of action, and common side effects
  3. Federal and state regulations governing practice

Equipment & Tools

FDA Orange Book determination that a generic is bioequivalent and substitutable for the brand. AB-rated substitution tested on PTCB exam.

Related drug class: Benzodiazepines includes lorazepam, diazepam, alprazolam, midazolam. Mechanism: Enhance GABA-A receptor, increased chloride conductance, CNS depression.

Why It Matters

AB-rated substitution tested on PTCB exam.

Related Terms

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Frequently Asked Questions

What sig codes are commonly seen with therapeutic equivalence prescriptions?
For therapeutic equivalence: TOP = topically, TID = three times daily, PRN = as needed, OU = both eyes, SL = sublingual.
What drug interactions should be monitored for therapeutic equivalence?
For therapeutic equivalence: Statins (atorvastatin, rosuvastatin, simvastatin): Myalgia/myopathy; Hepatotoxicity (monitor LFTs); Rhabdomyolysis (rare); Take simvastatin/lovastatin in evening. Always check for drug interactions before dispensing.
What calculations are involved in therapeutic equivalence?
For therapeutic equivalence: flow rate: Volume (mL) * drop factor / time (min). Example: 1000mL * 15gtt/mL / 480min = 31.25 gtt/min.