different routes of drug administration and their advantages and disadvantages

1. Name Laraib Tariq
Department pharm D
Semester 3rd
Subject Pharmacology
Topic Routes of drug administration

3. ROUTES OF DRUG ADMINISTRATION:
Definition:
 Route of administration is the pathway followed by any
substance ( drug, fluid, poison etc) to reach into body (targeted
area).
 Route of administration affects the drug bioavailability and help us to
determine the pharmacological effects.
 Various properties can determine the route of drug administration
e.g;
1.Properties of drug
(water, lipid soluble, ionization)
2.Therapeutic effect
(rapid or slow onset of action)

4.  Following are the routes of drug administration.

5. ENTERAL ROUTE:

6. ENTERAL ROUTE:
 The safest, popular and simple form of medication is enteral
administration (by mouth) into GI track. Both ends of GIT can
be utilized, the mouth and the anus. The medication can be
taken by several ways e.g can be positioned under the
tongue( sublingual), between the gums( buccal) and cheeks.
They promotes the direct absorption into the bloodstream.
 Enteral administration involves esophagus, stomach, small
and large intestine.
 The most common route in enteral is by ingesting them orally.

8. 1. Oral route:
 The first and best choice of drug administration is oral route since
it is convenient .Neither special knowledge nor special supplies are
required( syringes, needles).
 The instructions are easily understandable to the patients, reducing
the visit to the health centre. So it is advantageous to both patients
and physician.
 Can be easily self administered, without need of doctor.
 In some cases oral route is advantageous (toxicities can be
reversed by binding to activated charcoal) but also not suitable
for drugs which are affected by harsh acidic environment of
stomach (low gastric ph inactivates the drug).

9. ADVANTAGES AND DISADVANTAGES:

10. GASTRIC RESISTING PREPARATIONS:
 Sometime drugs are targeted to GI sites such as for
heart burn purposes, then in this case oral route is best
way of administering drugs. Therefore they must be
absorbed from GI system to gain access to systemic
circulation and reach the site of action.
 In this case drugs may be affected by GIT environment
because some drugs are poorly absorbed in GIT(
heparin) or some become irritating to stomach(aspirin).
 So in order to keep drug safe to reach into body, two
types of preparations are available.
1.Enteric coated preparations.
2.Extended release preparations.

12. 1:ENTERIC COATED PREPARATIONS:
 It is the polymer barrier that protects the drug release from
stomach acidic ( ph 3) environment to the intestine less acidic
( ph 7-9 alkaline) environment.
 It is also an efficient way to achieve drug target.
 Sometime certain Anthelmintic need to achieve high
concentration in certain sections of intestine so enteric coating
is best for such dosage form.
 So all the drugs which are damaged by stomach secretions or
cause gastric discomfort are administered in this form.
 Like aspirin, omeprazole etc cause severe gastric
discomfort, for such preparations enteric coating tends to
avoid activation and in mouth and esophagus.

13.  These preparations takes time from 30 mints to 7 hours to
reach to the intestine depending upon the type of food present
in stomach.
 Fatty acids, waxes, plant fibers and plastics are use for enteric
coatings.

14. 2:EXTENDED RELEASE PREPARATIONS:
 Extended release drugs have special coatings that promotes
the slow release of drug in GI fluids.
 It increase patient compliance and maintain concentration
within therapeutic range for a long period of time as compared
to immediate release dosage forms.
 Have duration of 8 hours or longer.

15. ADVANTAGES OF EXTENDED RELEASE
DRUGS:
 Decrease in frequency of administration of drug relative to
other dosage forms
 Maintain therapeutic range
 Lessens the intensity of undesired effects
 Lessens the drastically increase in blood level after
administration of other dosage forms.
 Beneficial for drugs having short half life.
 For example 2 doses of extended release morphine are
enough for pain relief relative to oral morphine which is
administered six times a day having half life of 2 to 4 hours.

17. SUBLINGUAL/BUCCAL:

18. SUBLINGUAL ROUTE:
 Sublingual means to place the drug under the tongue and
buccal means to place between cheek and gums as there is
high capillary network and promotes the drug to enter the
systemic circulation.
 This route is significant for highly soluble drugs by preventing
the first pass affect e.g nitroglycerine. If we take nitroglycerine
by oral route than more than half is cleared by first pass effect.

20. PARENTAL ROUTE:
 This route introduces the drug directly into systemic
circulation. It is route of choice for drugs that are poorly
absorbed or unstable in GIT( insulin and heparin), for
unconscious patients or for rapid onset of action.
 This pathway is good because it do not follow first pass effect
and have high bioavailability.

22. TYPES OF PRENTERAL ROUTE:

23. 1:Intravenous (IV):
 It is helpful for non orally absorbed drugs. IV allows speedy
affect and full level of control over the amount.
 It provides 100% bioavailability.
 No absorption relevant factors are found in IV because there
is rapid and full bioavailability.
 The patient response is accomplish with a precision which is
not possible by other doses.
 It is the singe way of giving the irritating solutions because if
we inject drug slowly then blood dilutes considerably.
 It is good for localize affects because drug is injected directly
into artery.

24.  Usually for patient comfort, veins of forearms( basal and
middle cephalic vein) or in the wrist( cephalic accessory and
medial ante-brachial) are most common sites for IV.
 In certain cases, it may be necessary to resort to a central IV
route, which consists in a catheter located at the outlet of the
superior vena cava (right atrium). This is required when it is
not possible to channel peripheral routes, for prolonged
treatments or when hypertonic solutions must be
administered.

25. IV INJECTION SITES:

26. Fast IV injection:
 The administration of single dose directly into the vein but in a
small volume. By this way the medication diluted in the
venous system is directly enter into the heart, pumped to the
lungs and spread to the rest of the body.
 Therapeutic affect start within 20 t 40 seconds thus useful
route for emergencies and pain management.
Slow IV injection:
 Administration into vein but in a large volume and for a long
period of time. Here medication enter the body by infusion
pump, forcing the solution to pass the catheter inserted in a
vein.

27. ADVANTAGES AND DISADVANTAGES:

28. 2:Intramuscular injections (IM):
 It is the administration of injection directly into the muscle in
different areas.
1. Upper part of arm: deltoid muscle is best target in this case
but it may be painful for patients because this area has
higher rate of absorption. 2ml amount is injected.
2. Glutes: dorsogluteal muscle is site of action in this case.
Here the rate of absorption is slow because of high amount
of adipose tissues.7-8ml amount is injected.
3. External thigh phase: vastus lateralus muscle are targeted
in this phase. This phase is usually for babies and infants
due to incompletely develop muscles. It may causes high
risk of nerve damage.5ml amount is injected.
 Aqueous solution medication are quickly absorbed depending
on the blood flow to the injection site. Some time local heat,
massage, or exercise can be modulated to some degree.

31. AQUEOUS AND DEPOT PREPARATIONS:
 Aqueous solutions are absorbed rapidly relative to depot
preparations which has slow absorption because they
consist of suspension of drug in non aqueous vehicle like
polyethylene glycol. First drug diffuse out of the muscle then
precipitates the site of action. It dissolves over an extended
period of time.
 Examples are haloperidol (sustained release drug) and
medroxyprogesterone.

32. 3:Subcutaneous (SC):
 It is the administration of drug injected under the skin into the
adipose layer beneath the dermis. So that is why also called
hypodermic administration.
 It is slower than IV injection. It provides the constant and
uniform affect. It is used for drugs that are not irritating to the
tissues otherwise causes severe pain and necrosis. It provide
prolong and slow action.
 We can alter the period of drug absorption as in insulin
injections depending upon the particle size, protein
complexation and Ph.
 Drug absorption implanted under the skin in a sold pellet form
occur slowly over weeks or months. This route is affected for
certain hormones e.g contraceptives.

33.  It is applied on the external side of arm or thigh or on the
anterior face of abdomen. Usually injected smaller amount
than IM.
 It minimize the risk of hemolysis or thrombosis as occur in IV.

35. IV ,IM AND SC INJECTION:

36. OTHERS:
1: Oral inhalation:
 Route for inhalation both oral and nasal gives the quick
delivery of medication due t large surface area of mucous
membrane in respiratory and pulmonary epithelium.
 This route is a fast as IV bolus ones.
 Gasses drug such as aerosol (anesthetics) and dispersed
form are given via inhalation.
 It is usually use for respiratory disorder patients( asthma or
pulmonary disorder patients) because drug is delivered
directly to the site of action without causing systemic side
effects.
 Example: bronchodilator, corticosteroid, albuterol.

38. 2:Nasal inhalation:
 In nasal route drugs are insufflated through the nose either in
the form of topical or systemic administration.
 These are locally acting drugs( such as decongestant for cold
and allergy treatment) having minimal systemic effects.
 Example of such drugs are migraine drugs, nicotine
replacement, hormone replacement, desmopressin( for
diabetes incipidus) and corticosteroids.

41. 3:Intrathecal:
 It is the administration of drug via injection into the spinal cord
or into the subarachnoid space so that it reaches the
cerebrospinal fluid and useful in spinal anesthesia,
chemotherapy or pain management applications. Use to treat
brain tumors.

42.  It is useful for drugs that fight against certain infections
specially post neuro-surgical.
 These drugs can easily cross the blood brain barrier and
specially compounded by the pharmacist or physician
because it can not contain any inactive constitutes relative to
other drugs given by injections(IV,IM,SC).
 Sometime it is referred as intrathecal because it means to
introduce something into the anatomic space or potential
space inside a sheath usually brain and spinal cord
arachnoids membrane (under which is the subarachnoid
space).
 Example: Intrathecal immunoglobulin development(for
production of antibodies in spinal cord)

43. Example:
 Intrathecal amphoterecin B
(to treat cryptococal meningitis)
 Intrathecal immunoglobulin development
(to produce antibodies in spinal cord)

44. 4: Topical:
 It means to apply on the mucous membrane via different
dosage forms e.g creams, lotions, gels etc. Usually used
when localize affect is require.
 These are epicutaneous means apply directly to the skin.
 They can be applied on the tissues other than skin surface
such as eye drops( to conjunctiva), ear drops( to ears), or
applied to surface of tooth.

45.  If we strictly say that it has local affect then it can be included
in enteral route of medication that has poor absorption in GI.
 Example: one poorly absorbed antibiotic is vancomycin,
which is recommended by mouth as a treatment of
Clostridium difficile colitis.
 Other examples are clotrimazole cream(for skin fungal
infection)

47. 5:Transdermal:
 It achieve systemic affect by applying to the skin usually in
form of patches. But the rate of absorption is different
depending upon the physical characteristic of skin, drug lipid
solubility.
 It is usually used for slow release of drugs such as
Nitroglycerine, the antiemetic scopolamine, and anti anginal
drug and nicotine transdermal patches( for smoking
cessation).
 In transdermal delivery drug passes through two sub-layers of
epidermis to reach into the dermis.

48.  Stratum cornium is the upper layer of the skin, thickness
varies from ten to hundred depending upon the body region.
 Its composition elements are flattened keratinocytes,
surrounded by lipid matrix that is difficult to penetrate.
 Stratum cornium is the significant barrier for transdermal drug
(90%).
 Below stratum cornium is the viable epidermis. Its thickness
is ten times as stratum cornium.
 But the rate of diffusion is faster here rather than the stratum
cornium because it has greater degree of hydration.
 Below epidermis lies dermis, approximately 1mm thick, 100
times more thick than stratum cornium. It contain vessels that
distribute drug into systemic circulation.

52. 6:Rectal route:
 Rectum is the ending portion of large intestine, 15cm long
from colon to anal sphincter. It is use for both local and
systemic affects.
 It is non keratinized surface, smaller than the duodenal
mucosa. Usually rectum is empty, occupied by few milliliters of
fluid ph ranging from 6-8 , and very viscous due to presence
of mucin. This characteristics of drug hinders drug absorption
since it imposes serious limitations to the drug dissolution
process.
 It is best use for drugs that are destroyed in GIT environment.

53.  Due to reduce surface area and shorter residence time, the
physiochemical characteristics of drug are critical factors.
 Generally lipophylic drugs are better absorbed than
hydrophilic, latter presents slow and incomplete absorption.
 This route is suitable for solid or liquid dosage form,
suppositories, jelly capsule or enemas.
 Absorption from aqueous and alcoholic solution occur slowly
and have great therapeutic effect. For example use of
diazepam for suppression of seizures.
 Suppositories absorption is slow. It depends upon drug
formulation, particle size, lipid solubility.
 Usually water soluble-base suppositories(release by
dissolution), low melting point fat bases(melt at body
temperature).
 Sometime contain emulsifying agent to keep drug dissolve in
it.

55. Thank you!