Intro to pharmacology - route of admn & basics

Question 1

Pharmacokinetics - what is it ? … mechanism ?

Answer 1

What the body does to the drug
- absorption
-distribution
-metabolism
-excretion

Question 2

Pharmcodynamics

Answer 2

what drug does to the body
includes : mechanism action + effect of the drug

Question 3

what constituets pharmcotherapy

Answer 3

prevention
treatment
diagnosis

Question 4

What are the principles in drug administration

Answer 4

Safety
Rationalizing
montioring
individualizing

Question 5

What is rationalisation of drug? & principles

Answer 5

drugs given match the clinical need
dosage must meet the individuls requirement
for an adequate period of time
at low cost for both community & patient
(effectiveness, safety, and cost-effectiveness of various drugs to make informed decisions about their use.)

Question 6

Effects of irrational prescription

Answer 6

Delay in cure
More adverse effects
loss patients confidence
Lowering health standards

Question 7

Causes of irrational prescription

Answer 7

Underprescribing - not enough dosage
Incorrect prescribing
Over prescribing

Question 8

How to choose best way to treat a condition?

Answer 8

-is drug therapy indicated ? and if so
-which drug is best for condition?
-which route is most effective ?
-which formulation ? capsule , rectum , serum
-Which dosage regimen? - during the night , after meals , day , how many times in a day.

Question 9

What is P-drug ( personal drug)

Answer 9

Drug that you have become familiar with and choose to prescribe regulary.
- all categories of drugs there is a p-drug (prototype drug)

Question 10

Advantages of P-drugs

Answer 10

Convinent
confidence
master easily
predictable
less complications
simpler healthcare management

Question 11

What are the major classification of routes of drug administration

Answer 11

Enteral
Paraenteral
Topical

Question 12

Describe Enteral & give examples

Answer 12

Def : delivery of drug through GIT(then absorbed) from the mouth
Example : oral , sublingual , rectal

Question 13

Define Parenteral & give examples

Answer 13

Def : delivery of drug directly into body through IV
Example:
- intravenous/intraarterial
- subcutaneous
- Intramuscular
- intradermally

Question 14

Define topical and give examples

Answer 14

Def: apply the drug directly onto the surface of skin / mucous membranes - allowing for local action of drug on the specific area applied
Examples
- Nasal(spray) , auditory(drops) , mucosal , conjunctival
- Vaginal & urethral
- Inunction (ointment , cream ) & dermal

Question 15

What are facotrs that govern the route of drug administration ?

Answer 15

1.Physical & chemical properties of drug
2.Rate & extent of absorption
3.effects of digestive juices - can it withstand
4.site of desired action
5.rapidity of desired response
6.accuracy of dosage
7.condition of patient - child cannot swallow tablets

Question 16

Advantages & disadvantages of Oral

Answer 16

Adv
1.Safe
2.Convenient
3.Economical
4.Usually good absorption
5.self administered
6.Painless

Disadv
1.Slow absorption
2.slow action
3.irritable & unpalatable(not pleasant) - can spit it
4.some drugs destroyed
5.First - pass effect

Question 17

Sublingual
-Location
-Advantages & Disadvantages

Answer 17

Site : under the tongue
Adv
1.Economical
2.Drug absorption quick - dissolved & absorbed directly in circulation
3.First pass avoided
4. self administered
5.quick termination - spit off

Disadvantages
1.Unpalatable & bitter drugs
2.Irritation of oral mucosa ( cause mouth ulcers)
3. Large quantities not given
4. High molecular weight drugs not absorbed - due to small spaces itd have to pass through

Question 18

Example of drugs administered sublingually (systemic & local)

Answer 18

Systemic use
- Isosorbide dinitrate
- nitroglycerine
- Nifedipine

Local
- antiseptic lozenge

Question 19

Advantages & Disadvantages of Rectal route

Answer 19

Advantages
1. Used in children
2. Little/no first pass effect (avoids 50%) - majority of drug absorbed
3. Used in vomiting /unconsious
4.Higher conc can be given
5.Can use gastric irritants

Disadvantages
1. embarrasing
2.inconvient
3.Absorption is slow & erratic
4. Irritation/ inflammation of rectal mucosa

Question 20

Examples of drugs given via rectal route . ( local & systemic)

Answer 20

Local
1.Dulcolax
2.Glycerine suppository
3.Enema - dissolve in oral mucosa
4.Ointment

Systemic
1.Aminophylline
2.Indomethacin suppositories

Question 21

Intradermal route
- Site
- advs & disadvantages
- example

Answer 21

Site : outer layer of skin
Adv
1.Used for testing sensitivity to drugs
2.high vascularity of dermis

Disadv
1.Painful
2.Amount of drug administered is small
3. Slow adsorption
4.Skin irritation

Example : BCG vaccine , allergic sensitivity test ,tubercullin test
uses tuberculin syringe 4

Question 22

Subcutaneous

Answer 22

Site: under skin ( deeper than intradermal)
Sites : gluteal , thigh , shoulder , back

Advs
1.Smooth but slow absorption
2.Depot injections , implants

Disadvantages
1.only Small vol (1ml )
2.irritant drugs = lead to necrosis
3. not suitbale in shock (vasoconstriction + redistibution of blood)

Question 23

Examples for subcutaneous route

Answer 23

Local : local anaesthetic
Systemic: insulin

Question 24

intramuscular
major sites
advantages & disadvantages

Answer 24

Major sites : deltoid , gluteus , vastus lateralis

Advantages
1.absorption reasonably uniform
2. rapid onset action
3. mild irritants can be given
4. first pass avoided
4.Gastric factors can be avoided

DIsadvantages
1. only up to 10ml given
2.local pain & abscess
3.Expensive
4.Infection
5.Nerve damage (sciatic nerve )

Question 25

Intravenous route advantages

Answer 25

1.Bypass first pass metabolism (100%) 2.quick onset of action 3.unccoperative & unconsoiious patients .vomiting & nausea 4. drugs of hypertonic solns & irritants 5.LArge volumes 6.Amount of drug can be controlled accurately

Question 26

Disadvantages of intravenous

Answer 26

1. Required antiseptic conditions - to prevent infection in blood 2. specialised skills 3.painful 4. cannot be recalled - wrong dosage is a wrong one 5. cause air embolism - lead e.g heart failure , pulmonary embolism 6. cannot give suspensions , oily drugs & depots 7. can cause extravastion / thrombophlebitis

Question 27

What is extravasation

Answer 27

escape of fluid from a blood vessel to surrounding tissue during IV cannulisation - painful & harmful

Question 28

Definition of Thrombophlebitis

Answer 28

irritation of vein during cannulation causing inflammation and leading to clot.

Question 29

Intra-arterial Site advantage Disadvantage example

Answer 29

Site: lumen artery Advantage: -greater conc of drug can be delivered Disadvantage -Expertise -Asepsis Example : radiopaque contrast for coronary angiopraphy & cerebral angiography

Question 30

Intraperitoneal Site Advantages & Disadvantages Examples

Answer 30

Site : peritoneal space Advantages - rapid absorption (due to large SA) Disadvantages - Painful - risky - adhesions -peritonitis example: dialysing fluid ( renal failure)

Question 31

Intrathecal(intraspinal) Site Advantages & disadvantages Example

Answer 31

Site: subarachnoid space Advantages - bypass Blood brain barrier Disadvantages - asepsis - expertise - painful - risky Example : radiopague contrast media , xylocaine injection

Question 32

Intramedullary Site Advantages & Disadvantages Examples

Answer 32

Site : tibia Advantages : rapid onset of action Disadvantages - strict asepctic conditions - expertise - painful - risky Examples : Emergency fluids in children

Question 33

Intracardiac injection site Examples

Answer 33

Left 4th intercostal space into heart muscle Example : cardiac arrest

Question 34

Intraarticular route site advantages & disadvantages Example

Answer 34

Site: directly into joint space Advantages: high conc in localised area DIsdavantages: - asepsis - joint damage - pain Example : - Hydrocortisone - Gold chloride

Question 35

Transdermal route what ? advantages

Answer 35

what? absorption of drug through skin for systemic action via a patch Advantages 1. stable blood levels - ( a particular mg permin) 2. no first pass metabolism Disadvantages 3. drug must be potent or patch will become too large potent meaning - administered effectively through a transdermal patch, the drug needs to be highly concentrated or potent. this is because, in a transdermal patch, the drug is absorbed through the skin over an extended period. If the drug is not potent, it would need to be present in large quantities in the patch to achieve the desired therapeutic effect, which would result in a very large or bulky patch.

Question 36

What is first pass effect

Answer 36

term used for hepatic metabolism of drug when it is absorbed from gut & delivered to liver via portal circulation The greater the first pass effect , the lower the bioavailability of the drug