Pharmaceutical Science Quiz

Introduction to Biopharmaceutics and Drug Dosage Forms/Databases

• The presentation covers biopharmaceutics, drug dosage forms, and drug databases.
• The presenter is Gretchen M. Ray, PharmD, PhC, BCACP, CDCES, an Associate Professor at the UNM College of Pharmacy.
• The date of the presentation is January 17, 2025.

Objectives

• Define biopharmaceutics
• Explain the relationship between pharmaceutical equivalence, bioequivalence, and therapeutic equivalence, and their relationship to generic drugs.
• Identify key counseling points and prescribing considerations for various outpatient dosage forms (capsules/tablets, solutions, suspensions, elixirs, transdermal).
• Locate drug dosage forms information within a drug reference (Lexidrug™).
• Locate information on drug administration, ADME characteristics, and safety of cutting or crushing dosage forms.

Supplemental Readings/References

• Shargel L, Yu AC. Applied Biopharmaceutics & Pharmacokinetics, 7e; 2016
• Allen LV, Ansel HC. Ansel's Pharmaceutical Dosage Forms and Drug Delivery Systems, 10e; 2014

Biopharmaceutics

• The relationship between the physical and chemical properties of a drug, its dosage form, and the route of administration determines the rate and extent of drug absorption.
  • Stages include drug release and dissolution, absorption, distribution, elimination, excretion, and metabolism, and the resulting pharmacological or clinical effect.

Biopharmaceutics (Continued)

• Design, stability, manufacture, release, rate of dissolution, and drug delivery to the site of action are key factors in biopharmaceutics.
• Dosage forms have varying impacts on these factors, and affect therapeutic decisions when prescribing.

Generic Drug Approval

• Generic and brand-name drugs aren't always identical.
• Generic drugs must contain the same active pharmaceutical ingredient, dosage form, and route of administration as the brand-name drug when the patent expires.
• A new drug application (NDA) is required for approval by the FDA, followed by a patent grant.
• To be equivalent, a generic drug is required by FDA rules to be a therapeutic equivalent, have similar rate and extent of drug reaching action site, and be pharmaceutically equivalent.

Generic Drug Approval (Continued)

• Generic drug approval requires demonstrating therapeutic equivalence to the brand drug (safe and effective) and pharmaceutical equivalence (identical dosage form containing the same amount of active pharmaceutical ingredient).
• Generic drugs can have different inactive ingredients (excipients) such as colors or preservatives.

Routes of Administration and Associated Drug Dosage Forms

• Oral route is the most common.
• Oral dosage forms include tablets, capsules, suspensions, solutions, and elixirs.
• Rectal route is useful for unconscious patients or those vomiting.
• Suppositories are solid forms for the route.
• Parenteral route involves injections (subcutaneous, intramuscular, intravenous, and intradermal).
• Drugs can have systemic (whole body) absorption, or local absorption with minimal systemic effects.

Oral Route/Oral Dosage Forms

• Tablets are compressed solid dosage forms.
• Capsules contain a drug and filler enclosed in a hard or soft gelatin shell. Unfused capsules can be opened.
• Suspensions involve insoluble drug particles in a liquid vehicle (must be shaken before use).
• Solutions are drug particles dissolved in a liquid vehicle.
• Elixirs are solutions in a hydroalcoholic vehicle,
• Syrups are sucrose-based solutions.

Rectal Route

• Advantage: useful for vomiting or unconscious patients who can't swallow; approximately 50% of the drug avoids the liver.
• Disadvantage: irregular and unpredictable absorption.
• Suppositories are a solid dosage form designed to melt or dissolve to release the drug.

Parental Route

• Advantages: rapid absorption, predictable drug levels; preferred for drugs destroyed by the gastrointestinal (GI) tract.
• Disadvantages: difficult to remove drug in overdose cases, sterility is essential, and trained personnel are needed.

Topical Routes

• Includes lotions, creams, and ointments.
• Transdermal patches are used for systemic absorption through the skin.

Ocular, Otic, and Nasal Routes

• Ophthalmic solutions, suspensions, and ointments are for the eyes. These have minimal systemic absorption.
• Otic solutions and suspensions are for the ears to create prolonged contact and minimal systemic absorption.
• Nasal solutions are administered as drops or mists and systemic absorption can occur leading to adverse events or drug interactions.

Modified Release Drug Products

• Immediate-release (IR) products release the drug immediately after administration.
• Modified-release forms alter the timing or rate of drug release.
• This improves patient adherence and control of drug absorption.
• Types include extended-release (controlled-release, sustained-release, long-acting).
• Delayed-release releases a portion of the drug at a time other than immediately after administration, enteric coated tablets, and repeat-action.
• Targeted-release releases the drug at or near its intended site of action.
• Orally disintegrating tablets (ODTs) disintegrate rapidly and can be swallowed without water.

Modified Release Drugs (Continued)

• Advantages: sustained therapeutic blood levels, improved patient adherence and tolerability.
• Disadvantages: dose dumping (sudden large release), less flexibility in dose adjustments, and potentially larger product sizes making high-dose administrations more challenging.

Clinical Considerations for Oral Modified Release Dosage Forms

• Do not switch between immediate and modified-release forms without consideration of existing blood concentrations.
• Counsel patients to not crush or chew modified-release tablets or capsules. Some modified-release products contain non-erodible plastic that can be seen in the stool.
• Check a drug resource in case of doubt (lexidrug™).

Modified Release via Transdermal Drug Delivery Systems (Drug Patches)

• Advantages: avoids GI tract absorption, avoids first-pass liver metabolism, can provide extended therapy, and have rapid termination.
• Disadvantages: only potent drugs can be delivered via patches as a dosage form, risk of skin irritation, variable absorption, delayed onset of action after application, and difficulty transitioning from patches to other formulations (like oral) medications frequently.

Clinical Considerations When Prescribing Drug Patches

• Ensure patients remove old patches before applying new ones.
• Apply to clean, dry skin without hair.
• Do not use concurrently with lotions or emollients due to increased skin permeation.

Practice with Drug Database

• Lexi-Comp is an open database that can be used to search for drug information, such as preparations, dosage forms, administration guidelines, pharmacology and pharmacokinetics, pharmacodynamics, ADME characteristics, and appropriate use/handling considerations (e.g., whether it's safe to cut a certain medication).
• Examples for use include Amoxicillin, Promethazine, and Pantoprazole to search for usage information.