Drug Regulation and Prescription Writing Flashcards
“Bioequivalence” involves which step of pharmacokinetics?
The absorption step.
How do generics compare to brand name drugs in terms of ingredients, effect, quality, and bioavailability?
Generics contain the same active ingredient, thus the pharmacological effects are the same. Generic products are cheaper, but not inferior if they are approved but the FDA. (Not always greatly cheaper, companies still make money). Most generics are bioequivalent to brands, with an average variation in bioavailability of <4%. Thus if the therapeutic window is not too narrow (angina, seizure disorders, etc.) generics save $$$.
Three types of drugs that should not be switched to generics.
Those with narrow therapeutic windows (levothyroxine - anitseizure med). Those with non-linear (zero order) pharmacokinetics (phenytoin). Those with poor bioavailability. The pharmacist can substitute as per state laws, but the prescribing physician has the final say.
Three types of equivalence and their meaning.
Pharmaceutical Equivalence - The drug formulation. Bioequivalence - drug passes the absorption step and molecules are present in the blood. Therapeutic Equivalence - The drug has the exact same therapeutic effect.
What equivalence is required for FDA approval of a generic?
Bioequivalence is required. Generics may have different drug formulations, thus they are not pharmaceutical equivalents. Also, the manufacturers are not required to redo the same clinical trials that proved efficacy and safety of the original product (therapeutic equivalence). Bioequivalence may be tested by administering the generic and the brand drug to different sets of volunteers and measuring the amount present in the blood stream.
What does bioequivalence show?
It DIRECTLY MEASURES bioavailability, which shows what percentage of the drug gets in via the oral route vs IV. It also ESTIMATES rate of the maximum Cp reached and the time that it was reached (mg/hr). Bioequivalent products are considered to be therapeutic equivalents.
Define pharmaceutical equivalents and pharmaceutical alternatives.
Pharmaceutical equivalents have the same active ingredient, same dosage formulation (tablet, capsule, solution, etc), same route of administration, and are identical in strength or concentration. Alternatives can have the same therapeutic moiety but different salts, esters, or complexes of that moiety, different dosage forms (tablet vs capsule), diff strengths (200mg vs 250mg), different release rates. Alternatives are NOT interchangeable.
What does bioequivalence testing ultimately show?
To be bioequivalent, you have to start with a pharmaceutical equivalent, and then measure the rate and extent (bioavailability). Thus, the testing is of the product formulation. Bioavailability is the pharmacokinetic parameter that is used to describe the absorption characteristics from a route of a specific drug. Bioequivalence tests the rate at which the formulation dissolves and becomes bioavailable.
What is the range of error that a generic must fall within to be considered bioequivalent?
The 90% confidence interval of the generic’s AUC and C-max or T-max must fall completely within 80-125% of that of the brand. The difference between the mean values is only 4%.
What claims are supplements barred from making and what claims are they allowed to make?
Dietary supplements cannot make HEALTH CLAIMS, that describe effects on reducing risk of or preventing a disease. HEALTH CLAIMS require FDA approval. Supplements may make STRUCTURE/FUNCTION claims which describe that the substance maintains the structure or function of the body. They do not need FDA approval, but cannot mention specific diseases.
Who enforces violations regarding the claims made by supplement manufacturers?
The Federal Trade Commission (FTC).
What information is required and notably not required on a dietary supplement?
The name of the product, net quantity of contents, manufacturer information, and directions for use are all required. The identification of the active compound, pharmacokinetic data, and potential interactions with Rx or OTC medications are notably not required.
What standards and requirements are there for supplements?
There are no legal or regulatory definitions of standards, but manufacturers may submit their products for testing as to product identity, purity, quality, strength and packaging. Those that do may display DSVP certifications. FDA now enforces Good Manufacturing Practice including quality control procedures for plants and tests final products for identity, purity, and strength.
Where can you find more information on dietary supplements?
Natural Medicine Comprehensive Database (NMCD)
What are the three classes of drugs limited to prescription use?
Certain habit forming drugs (Controlled Substances), Drugs not safe for use without supervision of a licensed practitioner due to toxicities, method of use, or collateral measures necessary for use, and drugs limited to prescription use under an NDA.
