Biological Barriers to Drug Absorption (I,II) PDF - RCSI Medicines 1

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Biological Barriers to Drug Absorption (I, II) Course: Masters in Pharmacy (MPharm), BSc Advanced Therapeutic Technologies Module: Medicines 1 Lecturer: Dr Sam Maher LEARNING OUTCOMES 1. Describe the types o...

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Biological Barriers to Drug Absorption (I, II) Course: Masters in Pharmacy (MPharm), BSc Advanced Therapeutic Technologies Module: Medicines 1 Lecturer: Dr Sam Maher LEARNING OUTCOMES 1. Describe the types of epithelia and endothelia that control drug absorption 2. Outline the routes of drug transport across epithelia 3. Recall how efflux pumps can influence drug absorption 4. Recall how blood flow can influence absorption 5. BIOLOGICAL BARRIERS FROM PILL TO RECEPTOR TYPES OF EPITHELIA AND DRUG PERMEABILITY TYPE DESCRIPTION LOCATION PERMEABILITY SIMPLE SQUAMOUS Single layer of Lining blood Excellent flattened, vessels interlocking cells Alveoli SIMPLE COLUMNAR Single layer of Stomach Very good rectangular cells Small intestine Upper respiratory STRATIFIED Multiple layers of Buccal & Intermediate to SQUAMOUS flattened, sublingual very good NON-KERATINISED nucleated cells, Lower pharynx suited for abrasion Oesophagus Vagina Conjunctiva Cornea STRATIFIED Multiple layers of Hard palate Poor SQUAMOUS flattened, non- Gums KERATINISED nucleated cells, Nasal vestibule suited for abrasion Skin The bodies surfaces intended for absorption are 1 cell thick Body surfaces tasked with greater barrier properties are covered with multiple layers of epithelial cells  CAPILLARY PERMEABILITY LOCATION CAPILLARY DESCRIPTION PORE SIZE SKIN Continuous 5nm MUSCLE Tight junctions (loose) ADIPOSE LUNG INTESTINAL MESENTERY HEPATIC Sinusoidal 180nm Open fenestrae CONNECTIVE TISSUE Fenestrated 6-15nm RETINAL Continuous