Generic vs Brand Name Drugs: What Pharmacy Techs Must Know

Generic vs. Brand Name Drugs in Pharmacy Practice

Understanding the relationship between generic and brand name drugs is fundamental to pharmacy practice. Generic drugs account for roughly 90% of all prescriptions dispensed in the United States, making them one of the most important topics for pharmacy technicians. This guide covers the science behind generic drugs, substitution regulations, and what the PTCB exam expects you to know.

What Makes a Drug Generic?

A generic drug contains the same active ingredient, in the same dosage form, at the same strength, and by the same route of administration as the corresponding brand name product. Generic drugs must meet the same FDA quality standards for purity, potency, and stability as their brand name counterparts.

The key difference is that generic manufacturers do not need to repeat the extensive clinical trials performed by the original manufacturer. Instead, they must demonstrate bioequivalence, meaning the generic drug delivers the active ingredient to the bloodstream at the same rate and to the same extent as the brand name drug.

The FDA Approval Process for Generics

Generic drugs are approved through an Abbreviated New Drug Application (ANDA). The ANDA process requires manufacturers to demonstrate that their product is pharmaceutically equivalent and bioequivalent to the reference listed drug (the brand name product). The FDA reviews all manufacturing processes, quality control measures, and labeling before granting approval.

Bioequivalence testing typically involves giving both the generic and brand name drugs to a group of healthy volunteers and comparing blood levels over time. The generic product must deliver the active ingredient within 80-125% of the brand name product's rate and extent of absorption to be considered bioequivalent.

Why Generic Drugs Cost Less

Generic drugs are significantly less expensive than brand name drugs because generic manufacturers do not bear the costs of drug discovery, extensive clinical trials, and initial marketing. When a brand name drug's patent expires (typically 20 years from the patent filing date), other manufacturers can produce generic versions, creating competition that drives prices down.

Additionally, multiple generic manufacturers often produce the same drug, further increasing competition. The FDA encourages generic drug development through various incentives, including 180-day exclusivity periods for the first generic applicant.

Therapeutic Equivalence and the Orange Book

The FDA's Orange Book (officially titled "Approved Drug Products with Therapeutic Equivalence Evaluations") is the definitive reference for determining whether generic drugs are therapeutically equivalent to their brand name counterparts. Understanding the Orange Book rating system is important for pharmacy technicians:

• A-rated products are considered therapeutically equivalent and can be substituted for the brand name drug. The most common A-rating is AB, which indicates bioequivalence has been demonstrated through in vivo testing.
• B-rated products are NOT considered therapeutically equivalent and should not be automatically substituted. These products may have known bioequivalence problems or insufficient data to support equivalence.

When in doubt about a generic substitution, checking the Orange Book rating ensures that the substitution is appropriate and approved by the FDA.

Generic Substitution Laws

Generic substitution laws vary by state, but most states allow or require pharmacies to substitute A-rated generic drugs unless the prescriber specifically indicates otherwise. Common prescriber notations that prevent generic substitution include "DAW" (Dispense As Written), "Brand Medically Necessary," or "No Substitution."

DAW codes used in pharmacy billing include:

• DAW 0 - No product selection indicated (generic substitution allowed)
• DAW 1 - Substitution not allowed by prescriber
• DAW 2 - Substitution allowed, patient requested brand
• DAW 3 - Substitution allowed, pharmacist selected brand
• DAW 4 - Substitution allowed, generic not in stock
• DAW 5 - Substitution allowed, brand dispensed as generic

Narrow Therapeutic Index Drugs

Some medications have a narrow therapeutic index (NTI), meaning there is a small difference between the effective dose and the toxic dose. For NTI drugs, even small variations in blood levels can cause significant clinical effects. Examples include warfarin, levothyroxine, digoxin, lithium, phenytoin, and carbamazepine.

While generic versions of NTI drugs are still FDA-approved and bioequivalent, many pharmacists and prescribers exercise extra caution with these medications. Some states have specific rules about substitution of NTI drugs, and many clinicians prefer that patients remain on the same manufacturer's product once stabilized.

Inactive Ingredients and Allergies

While generic drugs contain the same active ingredient as the brand name product, the inactive ingredients (excipients) may differ. Inactive ingredients include binders, fillers, dyes, preservatives, and flavoring agents. Some patients may have allergies or sensitivities to specific inactive ingredients, which could make a particular generic formulation unsuitable for them.

Pharmacy technicians should be aware that switching between different generic manufacturers, while pharmacologically equivalent, may occasionally result in patient complaints about differences in appearance, taste, or perceived effectiveness. These concerns should be communicated to the pharmacist for clinical evaluation.

PTCB Exam Essentials

For the PTCB exam, focus on understanding the ANDA approval process, Orange Book therapeutic equivalence ratings, DAW codes and their meanings, the concept of bioequivalence, and common generic and brand name drug pairs. Being able to quickly identify whether a drug is generic or brand name by its naming conventions is also valuable, as brand names are capitalized and generic names are lowercase.