Absorption 2024 Student Version PDF

Absorption Zackery P. Bulman, PharmD [email protected] Associate Professor Department of Pharmacy Practice College of Pharmacy University of Illinois at Chicago Learning Objectives 1) Identify routes of administration that...

Absorption Zackery P. Bulman, PharmD [email protected] Associate Professor Department of Pharmacy Practice College of Pharmacy University of Illinois at Chicago Learning Objectives 1) Identify routes of administration that require absorption 2) Define advantages and disadvantages of oral drug administration 3) Understand and describe the major physiologic factors that affect oral drug absorption 4) Understand and describe the major physiochemical factors that affect oral drug absorption Absorption Movement of the drug from the site of administration to the bloodstream Sites of administration vary and dictate absorption barriers Concentration gradient between blood and site of drug administration encourages absorption Systemic Routes of Administration: Parenteral Parenteral = administration outside gastrointestinal tract Examples Intravenous Absorption phase following Intraarterial parenteral administration is either Intramuscular avoided altogether or occurs at the site of administration Subcutaneous Intrathecal Transdermal Intranasal Systemic Routes of Administration: Enteral Enteral = administration inside gastrointestinal tract After oral administration, absorption can occur Examples throughout the Buccal intestinal tract Sublingual Oral (PO) Small intestine is the Rectal major site of absorption Routes of Administration Requiring Absorption Some routes of administration do not require absorption Avoids Absorption Phase Absorption Required Intravenous Intramuscular Intraarterial Subcutaneous Intrathecal Oral Buccal Sublingual Transdermal Intranasal Oral Absorption Oral Route of Administration Advantages Convenient, palatable dosage forms Cheaper than most parenteral formulations Can administer in outpatient setting Disadvantages Can be inefficient: multiple barriers to get to systemic circulation Local side effects sometimes significant (eg. nausea) Variable absorption can alter pharmacokinetic profile  Sites of Absorption after Oral Administration Drug Transit Site pH Length (m) Surface Area (m2) Time Stomach 1-3 0.3 0.5 hr. 0.2 Duodenum 5.8-6.5 0.3 Capsule > Tablet > Extended Release Tablet Assuming same drug given in all formulations Increasing thickness of diffusion layer or decreasing surface area Factors Affecting Oral Absorption: Physiochemical Dissolution: Can reduce particle size to increase surface area Ex. Micronized griseofulvin Can increase particle size to decrease surface area Ex. Nitrofurantoin macrocrystals Macrobid: 75% nitrofurantoin monohydrate 25% nitrofurantoin macrocrystals Factors Affecting Oral Absorption: Physiochemical Which of the following drug formulation alterations would help extend the release of your newly developed compound to provide prolonged exposure? Select all that apply. A. Increase surface area (S) B. Decrease surface area (S) C. Increase thickness of diffusion layer (h) D. Decrease thickness of diffusion layer (h) Factors Affecting Oral Absorption: Physiochemical Molecule Size: In general, smaller sized drugs are better absorbed orally because they pass through the epithelial cells better Goal: molecular mass