6. Some drugs are taken as smaller tablets which are held in the mouth or under the
tongue.
• Advantages
rapidabsorption (angina pectoris)
drug stability
avoidfirst-passeffect
7. • Disadvantages
Inconvenient for all drugs .
small doses
unpleasant taste of some drugs
E.g. of sublingual drugs:Trinitroglycerin, Borbrinpherin
E.g. of buccal drug: Nicotine
10. Advantages
Convenient - can be self- administered, pain free, easy to take
Absorption - takes place along the whole length of the GI tract
Cheap - compared to most other parenteral routes
11. Disadvantages
Sometimes inefficient - only part of the drug may be absorbed
First-passeffect - drugs absorbed orally are initially transported to the
liver via the portal vein
irritation to gastric mucosa - nausea and vomiting
12. Disadvantages cont.
destructionof drugs by gastric acid and digestive juices
effect too slowfor emergencies
unpleasant taste of some drugs
unable to use in unconscious patient
الهضمي الجهاز بحركية يتأثروالطعام تناول أو أخرى أدوية بإعطاء(المث:قديفاقم
الميتوكلوبراميداألدوية بعض امتصاص)وبمدىاستقلبللدواء الكبدErالممتص(تأثير
األول العبور),المث:يتخرب75%منالبروبرانولالممتص(ذلك من وأكثر
للكيتامين)الكبد ضمن األول العبور لدى.
بي األمعاء ضمن كامل أو كبير بشكل األدوية بعض فعالية زالُت حال كل علىيتأثر ال نما
اآلخر البعض
13. The first-pass effect is the term used for the hepatic metabolism of
a pharmacological agent when it is absorbed from the gut and
delivered to the liver via the portal circulation. The greater the
first-pass effect, the less the agent will reach the systemic
circulation when the agent is administered orally
14. Magnitude of first pass hepatic effect:
Extraction ratio (ER)
ER = CL liver / Q ; where Q is hepatic blood flow (usually
about 90 L per hour.
Systemic drug bioavailability (F) may be determined from the
extent of absorption (f) and the extraction ratio (ER):
F = f x (1 -ER)
23. •Mucosal membranes (eye drops, antiseptic, sunscreen,
callous removal, nasal, etc.)
•Skin
a. Dermal - rubbing in of oil or ointment
(local action)
b. Transdermal - absorption of drug through skin (systemic
action)
i. stable blood levels
ii. no first pass metabolism
iii. drug must be potent or patch
becomes to large
31. 1.gaseous and volatile agents and aerosols
2.rapid onset of action due to rapid access to circulation
a.large surface area
b.thin membranes separates alveoli circulation
c.high blood flow
Particles larger than 20 micron and the particles impact in
the mouth and throat. Smaller than 0.5 micron and they
aren't retained.
32. Respiratory system. Except for IN, risk hypoxia.
Intranasal (snorting) Snuff, cocaine may be partly oral via post-
nasal dripping. Fairly fast to brain, local damage to septum. Some
of the volatile gases also appear to cross nasal membranes.
Smoke (Solids in air suspension, vapors) absorbed across lung
alveoli: Nicotine, opium, THC, freebase and crack cocaine, crystal
meth.Particles or vapors dissolve in lung fluids, then diffuse. Longer
action than volatile gases. Tissue damage from particles, tars, CO.
Volatilegases: Some anaesthetics (nitrous oxide, ether) [precise
control], petroleum distillates. Diffusion and exhalation (alcohol).
Lung-based transfer may get drug to brain in as little as five
seconds.
34. Intravascular (IV, IA)- placing a drug directly into the blood stream
Intramuscular (IM) - drug injected into skeletal muscle
Subcutaneous - Absorption of drugs from the subcutaneoustissues
36. Absorption phase is bypassed
(100%bioavailability)
1.precise, accurate and almost immediate onset of action,
2. large quantities can be given, fairly pain free
3. greater risk of adverse effects
a. high concentration attained rapidly
b. risk of embolism
38. 1. slow and constant absorption
2. absorption is limited by blood flow, affected if circulatory
problems exist
3. concurrent administration of vasoconstrictor will slow
absorption
40. Oral - controlled-release, timed-release, sustained-release
designed to produce slow,uniform absorption for 8 hours or
longer
better compliance, maintain effect over night, eliminate
extreme peaks and troughs
41. Depot or reservoir preparations - parental
administration (except IV), may be prolonged by
using insoluble salts or suspensions in non-aqueous
vehicles.
42. The ROA is determined by the physical
characteristics of the drug, the speed
which the drug is absorbed and/ or
released, as well as the need to bypass
hepatic metabolism and achieve high
conc. at particular sites
Important
Info
43. No single method of
drug administration
is ideal for all drugs
in all circumstances
Very Important
note!
44. Polt ghraph of different dosage forms and it’s plazma concentrations