Dosage Forms and Drug Delivery Flashcards (Week 2)

Flashcards covering pharmaceutical dosage forms, routes of administration, GI absorption factors, gamma scintigraphy, and narrow therapeutic index drugs.

Enteric-coated tablets

Coated tablets designed for acid-labile drugs that are unstable at low stomach pH after oral intake.

Oral Route of Administration

Taken by mouth; the most common and convenient route, ideal for self-administered, systemic treatment.

Parenteral Administration

Refers to any routes of administration that do not involve drug absorption via the GI tract (par = around, enteral = gastrointestinal).

Intravenous (IV) Administration Advantages

Rapid achievement of concentration, precise delivery of dosage, and easy titration of dose.

Topical Dermatological Products

Products designed to deliver drug into the skin in treating dermal disorders, with the skin as a target organ.

Transdermal Products

Products designed to deliver drugs through the skin (percutaneous absorption) to the general circulation for systemic effects, with the skin not being the target organ.

Hepatic First-Pass Metabolism

Metabolism in the liver that reduces the potency of conventional oral drug delivery systems before reaching systemic circulation.

Rectal Route Absorption

Route where approximately $50\%$ of the dose absorbed may bypass the liver.

Buccal Administration

An oral dosage form designed to dissolve slowly on the cheek.

Sublingual Administration

An oral dosage form involving small tablets placed underneath the tongue.

Small Intestine Sections

Consists of the duodenum, jejunum, and ileum, which are responsible for absorbing digested nutrients.

Ileum Surface Area

The region in the gastrointestinal tract with the largest surface area, measuring $280\,m^2$.

Vital Absorption Factors

The two essential factors required for compounds to be effectively absorbed: solubility and permeability.

Excessively Hydrophilic Drugs

Highly water-soluble drugs showing poor absorption because they cannot effectively cross cell membrane lipid components.

High Lipophilicity Consequences

Linked with substances metabolized too quickly, causing drug candidates to be discontinued during testing.

Food-Drug Complexation

Occurs when calcium in dairy or antacids binds tetracycline and ciprofloxacin, reducing their absorption.

CYP3A4 Inhibition by Grapefruit

An interaction where grapefruit inhibits CYP3A4, an enzyme responsible for metabolizing many drugs.

P-glycoprotein (P-gp)

An intestinal efflux transporter that can be interfered with by CoQ10.

Timing of Food Relative to Drug Absorption

Minimizes food's effect on drug absorption when taken $2$ or more hours after a meal.

Gastric Emptying Rate in Diabetes

Accelerated in most people with type 1 and type 2 diabetes compared to those without diabetes.

Restrictive Bariatric Surgery

Procedures such as gastric banding and gastroplasty that decrease stomach size from about six cups to one.

Roux-en-Y Gastric Bypass

The most common weight loss surgery in the U.S. that combines restrictive and malabsorptive approaches to reduce stomach size and prevent calorie absorption.

Dumping Syndrome

Rapid movement of stomach contents into the small intestine post-surgery that can alter the timing and extent of drug absorption.

Gamma Scintigraphy

A non-invasive imaging technique using gamma-ray-emitting radioactive tracers attached to a drug formulation to track its movement inside the body.

Neutron Activation

The process of exposing a product with a stable tracer to a neutron flux to convert it into a gamma-ray-emitting radionuclide.

Samarium-152 Oxide

A non-radioactive tracer incorporated into a dosage form during manufacturing for neutron activation in gamma scintigraphy.

Pharmacoscintigraphy

Combination of gamma scintigraphy with pharmacokinetic testing performed simultaneously to link drug location with blood concentration.

Enterion Capsule

A capsule system with a $1.0\,ml$ drug reservoir capacity used for regio-specific gastrointestinal evaluation of formulations.

In Vitro Permeation Rank Order

The permeability rank order in human models across GI sites: antipyrine (high), atenolol (moderate), and desmopressin (low).

SNAC

Sodium N-(8-[2-hydroxybenzoyl]amino)caprylate, an absorption enhancer used to power oral semaglutide (Rybelsus).

Pepsin Inactivation by SNAC

Raises the local pH around the tablet to inactivate pepsin, preventing peptide breakdown.

Epithelial Membrane Fluidization

Mechanism by which SNAC fluidizes the cell membrane to create temporary openings for semaglutide absorption across the stomach wall.

Narrow Therapeutic Index (NTI)

A characteristic where small absorption swings or dosage changes lead to big clinical effects or toxicity.

Levothyroxine Solubility Requirement

Requires an acidic stomach to dissolve, with absorption impaired by PPIs, H2 blockers, and food/supplements.

Warfarin

A narrow therapeutic index drug monitored via INR that is sensitive to vitamin K in diet and has many drug interactions.

Phenytoin

An anti-seizure NTI drug with nonlinear (zero-order) kinetics affected by food, tube feeds, and generic switches.

Digoxin

A heart/arrhythmia NTI drug with toxicity close to its therapeutic dose, affected by food and GI motility.

Cyclosporine / Tacrolimus

Transplant NTI drugs whose levels are increased by grapefruit juice and require regular blood level monitoring.

Common Features of NTI Drugs

(1) Narrow gap between therapeutic and toxic doses, (2) absorption easily disrupted, and (3) requirement for ongoing lab monitoring.

Intrathecal Route

Delivery directly into the cerebrospinal fluid, used for pain management to avoid the blood-brain barrier (BBB).