Various routes use for the drug administration in bio-pharmaceutics . Also contains factors which should be taken into consideration.

1. Presented by:
Yusuf Nawaz Khan
RY1507A06

2. • May be classified as
• Enteral
• Parenteral.
• Enteral means through the GI tract and includes
oral, buccal, and rectal.
• Parenteral means not through GI and commonly
refers to injections such as IV, IM, and SC; but
could also include topical and inhalation.
• They have to cross at least one membrane
before reaching the systemic circulation (except
in IV).

3. Buccal/Sublingual Administration
• Drug is taken as smaller tablets which are held
between cheek and gum or under the tongue.
• Buccal tablets are often harder tablets, designed
to dissolve slowly ; on the other hand sublingual
tablets are having less hardness to show fast
action.
• Main barrier is epithelial of oral mucosa.
• This ROA is also used for some steroids such as
testosterone and oxytocin; other than that we
are using antianginal drugs.
• Mainly passive diffusion is major mechanism of
absorption.
• Nutrients can follow carrier mediated process.

4. Advantage and disadvantage
• Advantages –
i. Rapid absorption due to high vasculature.
ii. No first pass hepatic metabolism.
iii. No degradation due to neutral pH of saliva.
• Disadvantages –
Only small dose can be given due to limited mucosal surface
area.

5. Factors affecting absorption
i. Lipophilicity of the drug:
• Slightly higher lipid solubility required than for GI absorption.
ii. Salivary secretion:
• Drug must be soluble in aqueous buccal fluid.
• Absorption is delayed if mouth is dry.
iii. pH of the saliva:
─ Favorable absorption rate for drug unionised at pH 6.
iv. Binding to oral mucosa:
• Binding decreases bioavailability.
v. Thickness of oral epithelium:
• Sublingual faster than buccal.

6. Topical Administration
Drug can diffuse by-
• Intracellular (passive diffusion)
• Intercellular (paracellular)
• Transappendageal –
i. Hair follicles.
ii. Sweat glands.
iii. Sebaceous glands.
Main barrier is stratum corneum.

7. Factors affecting absorption
• Thickness of stratum corneum- absorption is slow in foot and
more in palm.
• Presence of hair follicles – more in follicles regions.
• Trauma- increase absorption.
• Hydration – promotes absorption.
• Age – infants absorbs more than adults.
• Ionized and soluble drug absorbs more.
• Permeation enhancer increase absorption.
• Exposer to chemical enhance absorption by shedding off of
stratum corneum.
• Chronic use of keratolytic enhance penetration.

8. Rectal Administration
• Most commonly used for suppository or enema.
• Some drugs given by this route include:
• Aspirin, theophylline, paracetamol and barbiturates.
• Advantages:
• By-pass liver - Some of the veins draining the rectum lead
directly to general circulation - by-passing the liver.
• Useful for patients unable to take drugs orally or with younger
children.
• Disadvantages:
• Presence of fecal matter retards absorption.
• Slow absorption due to limited surface area.
• Not well accepted.

9. Intravenous Administration
• The drug is injected as a bolus or infused slowly over
hours in one of the superficial veins.
• The drug reaches directly into the blood stream
• Rapid injections are used to treat epileptic seizures,
acute asthma, or cardiac arrhythmias etc.
• No absorption barrier is there.
• Quick response is possible.
• Large dose can be given by infusion.
• Require trained personnel.
• Expensive and chances of toxicity or infection.

10. Intramuscular
Administration
• Absorption is rapid but in comparison to i.v. it is slower.
Factors affecting absorption
i. Vascularity at injection site –
(deltoid)>(vastus lateralis)>(gluteus maximus)
ii. Lipid solubility and ionisation – highly lipid soluble drug are
more absorbed quickly and hydrophilic/ionised drug are
slowly absorbed by capillary pores.
iii. Molecular size – small molecules and ion go to capillary
through pores and larger go to lymphatic system.
iv. Volume and drug conc – Conc and high volume absorbed
rapidly.
v. pH and viscosity – drug solution in acidic/basic or
nonaqueous solvent result in slow release.

11. Subcutaneous Administration
• This involves administration of the drug dose just under the
skin.
• Absorption is slower in comparison to i.m.
• Important when rapid response is not required or drug
degrade when taken orally (insulin).
• Increasing the rate of absorption –
i. Enhancing blood flow – massage, applying heat,
vasodilators, exercise.
ii. Increasing drug-tissue contact time – administering enzyme
hyaluronidase.
• Decreasing the rate of absorption – Cooling , vasoconstrictors,
immobilization of limb.
• Mainly use controlled release medication.

12. Pulmonary Administration
• In principle we can use all systemic effective drug can be
administered.
• Only use for bronchodilator, anti-inflammatory steroids,
anesthetics and anti-allergic.
• Lipid soluble drug absorbed by passive diffusion.
• Polar drug by pore transport.

13. Nasal Administration
• Utilized only for local effects.
• For drugs that are destroyed in the GI
environment (or first-pass effect).
• As an alternative to intravenous administration
• Better safety and patient acceptance
Mechanism of drug transport-
i. Faster rate depend upon lipophilicity.
ii. Slower rate depend upon molecular weight.

14. Intraocular Administration
• Preparation should be sterile aqueous.
• Barrier is cornea (lipophilic + hydrophilic).
• Higher pH decrease tear flow and lower pH increase
lachrymation/decrease absorption.
• Small concentrated solution is more effective than large
volume/less concentrated.
• Oily or viscous solution are more effective.

15. Vaginal Administration
Drug intended to act locally-
i. In treatment of bacterial or fungal infection.
ii. To prevent conception.
• No first pass metabolism.
• Controlled delivery and termination of action when desired is
possible.

16. • Biopharmaceutics And Pharmacokinetics-
A Treatise By D.M.Brahmankar And Sunil B.
Jaiswal.