Drug Administration Lesson 3

Definitions n Pharmacokinetics l What the body does to the drug. l Administration, absorption, distribution, & fate l Focus of next 2 sections n Pharmacodynamics l What the drug does to the body. l drug effects l Coming soon ~

How To Get From Here To There? Drug Complex Journey ~ Target

Routes of Administration n Critical to efficacy l Rapidity of onset l Duration of effects l Magnitude of effects n Systemic administration l Drug into circulatory system via... u Enteral routes u Parenteral routes l Drug effects throughout body ~

Oral n Per Os (PO) u by mouth l absorption across membrane in GI l most common l most variable l 1 st pass metabolism n Cooperation required n Can recall ~

Oral n Sublingual l Absorption: u mucous membrane u salivary glands l e.g., nitroglycerin, buprenorphine n Chewing l absorbed across lining of mouth ~

Injection n Intravenous (iv) l directly into vein l rapid onset of effects u Fastest ~

Injection n Intramuscular (im) n Location important l Deltoid - rapid l Thigh - moderate l Buttocks - slowest l Difference in blood supply & distance ~

Injection n Subcutaneous (sc) l under skin l slow, steady absorption n Disadvantages l Variable absorption l limited volume l skin irritations ~

Injection n Intraperitoneal (ip) l into peritoneal cavity of abdomen l Can deliver large amounts n Not used in humans much l Danger of infection ~

Injection n Intrathecal (epidural) l under sheath of nerve fibers, spinal cord l Mostly as local anesthesia l little importance for psychoactive drugs ~

Injection n Intracranial l directly into brain l direct access to cells n intraventricular - into CSF n Peripheral vs. central effects l e.g. curare u peripheral ---> paralysis u central ---> convulsions ~

Inhalation n Smoking n Lungs l gases or vapors l densely lined with capillaries l large surface area n Fast absorption l Similar to iv ~

Intranasal n Particles of drug l insufflation = sniffed n Absorption across mucous membrane of nose l Not in lungs! n Slower absorption n effects not as strong as inhalation ~

Other routes n Transdermal patches l absorbed by skin l slow continuous release u also liposomes: via injection n Suppositories - rectal or vaginal l absorption incomplete & unpredictable n Pellets - Norplant n Microcatheter & pump ~

The Future: Part 1 n Polymer-to-gel l drug + water + biodegradeable polymer l 45 C: liquid & injectable l 37 C: solidified gel capsule l 70% of drug released over 12 days ~

The Future: Part 2 n Injections without NEEDLES!? l only some drugs enter via patch u e.g. nicotine, scopolamine n VLF - very low frequency sound l disrupts lipid layer of skin l more room for molecules to enter l insulin, interferon gamma, etc u works in rats & cadavers ~

Choice of route n Consider factors l Patient characteristics l Concentration in blood l Amount delivered l Rapidity of onset l Duration of effects l Magnitude of effects ~ related

In general... n Rapid onset of effects l higher magnitude l shorter duration n Slow onset of effects l lower magnitude l longer duration ~

Blood Level i.v. & inhalation im, sc, ip p.o. sec min hrhrs Time