Drug Delivery and Absorption

Anotações:

• Oral Pulmonary Per Rectal Intravenous Intramuscular Trnasfermal Opthamalic Subcutaneous

Anotações:

• 1. Most Drugs are weak acid/bases 2. Most drugs are lipophilic

Anotações:

• As usual, made up of phosphobilipid layer

1. Factors affecting drug access

   Anotações:

   • Molecular size and shape Degree of ionisation Relative lipid solubility of the ionised and non-ionised forms Bind affinity to receptor (membrane transport) proteins Normally, uncharged ones are the ones that are usable due to the affinity to the lipophilic layer. Extracellular concentration.
2. Methods of Traversal

   Anotações:

   • Pinocytosis Passive Diffusion Filtration Active Transport
   1. Passive Membrane Transport

      Anotações:

      • Ionization will affect and influence solublility and hence it is dependent on Ka and local pH
      1. pH in body

         Anotações:

         • Urine : 5 Small intestine : 7.8 Duodenum: 6 Saliva: 6 Stomach 1.3 Serum/blood: 7.4 CSF: 7.35
      2. Henderson-hasselbalch

Anotações:

• Degree of a drug becomes available to target tissue after administration Proportion of the administered dose that reaches the systemic circulation intact