Parenteral Fluids and medicines can be administered through catheter Catheter ·Intravenous(v.) ·Intramuscular(im.) ·Subcutaneous(Sc.) Intramuscular These e routes have the highest injection Subcutaneous injection bioavailability and are not subject t to Dermis first-pass metabolism or harsh 1G引 environments. For iv.delivery,absorption is complete (100%bioavailability). -Muscle Subcutaneous tissue一 11
Parenteral • Intravenous (iv.) • Intramuscular (im.) • Subcutaneous (sc.) 11 These routes have the highest bioavailability and are not subject to first-pass metabolism or harsh GI environments. For iv. delivery, absorption is complete (100% bioavailability)
Factors influencing absorption Related to Drugs Related to Body Water/lipid solubility pH Blood flow to the absorption site Molecular size Total surface area available for Degree of lonization absorption Route of administration Contact time at the absorption surface 12
Factors influencing absorption Water/lipid solubility Molecular size pH Blood flow to the absorption site Related to Drugs Related to Body 12 Degree of Ionization Route of administration Total surface area available for absorption Contact time at the absorption surface
Factors influencing absorption 1.Drug's chemical characteristics Water/lipid solubility,polarity: Diffusion drug lipid solubilityt absorption through lipid absorption1 0 polarity EXTRACELLULAR lonization: 70 MEMBRANE ionized -absorption unionized-absorption INTRACELLULAR Size:small size favours absorption. 13
1. Drug’s chemical characteristics Water/lipid solubility, polarity: drug lipid solubility↑ absorption ↑ polarity↓ absorption ↑ Factors influencing absorption 13 polarity↓ absorption ↑ Ionization: ionized - absorption ↓ unionized - absorption ↑ Size: small size favours absorption
Factors influencing absorption 2.Route of administration For iv.delivery,the drug is completely absorbed. absorption is faster from:Inhalation-Sublingual route →Rectal route→im.→sc.→Oral→Transdermal Intravenous Intramuscular Subcutaneous Oral Time Mode of application and time course of drug concentration 14
For iv. delivery, the drug is completely absorbed. absorption is faster from: Inhalation → Sublingual route → Rectal route → im. →sc. → Oral → Transdermal 2. Route of administration Factors influencing absorption 14
Example:Nitroglycerin(硝酸甘油) NDC037R9112,16 MYLAN NITROGLYCERIN TRANSDERMAL SYSTEM 0.4 mg/hr ao.cm) c Coni1Sysem 周 Route Onset IV (intravenous) immediate SL (sublingual) .......1-3min Transdermal ....... .......40-60min 15
Example: Nitroglycerin（硝酸甘油 ） 15 Route Onset IV （intravenous ） +..++++.+. +. immediate SL （sublingual ） +++.+++++++1-3 min Transdermal +++.+.+++++.. +. +40-60 min