Drug Formulation and Delivery

Question 1

List ideal characteristics of a diagnostic drug

Answer 1

Easy to administer
Rapid onset of effect
Sufficient duration of effect until procedure takes place
rapid recovery
cheap , plentiful supply , long shelf life . easy to store
no adverse reactions
no interactions

Question 2

What are the sources of ophthalmic drugs

Answer 2

Inorganic
Organic
Synthesised

Question 3

List the different forms of ophthalmic drugs

Answer 3

Aqueous solutions 
oily solutions 
ointments 
creams
colloidal solutions emulsions , suspensions , gels

Question 4

Passage of drug inot the internal structure of the eye is mostly done through which structure of the eyes

Answer 4

cornea

less than 20% via conj and sclera

Question 5

The cornea is often described as a fat water fat sandwich what is meant by this ?

Answer 5

epithelium - lipophillic
stroma - hydrophillic
endo - lipophillic

Question 6

what percentage of an aqueous drop will reach the anterior chamber?

Answer 6

1%

Question 7

Topical Anaesthetics are used prior to which types of procedures

Answer 7

invasive = tonometry and foreign body removal

Question 8

Pre tx with TA

Answer 8

increases permeability of the cornea to drugs subsequently instilled
improve efficacy and faster effect of drug achieved

Question 9

Give an example of a TA drug that useful to as pre tx

Answer 9

Oxybuprocaine

Question 10

The max volume the conj sac can contain is

Answer 10

30 microlitres

Question 11

Within the conj sac , the tear volume is approx ..

Answer 11

8-10 microlitres

Question 12

State the volume of drug dispensed by a dropper bottle

Answer 12

Approx 27 ML

Question 13

Instilling too much drug in the eye can cause

Answer 13

• drainage via nasolacrimal system

- overflow down face and cheek

Question 14

If several drops are required to be instilled , what should you do ?

Answer 14

ensure you leave enough time inbetween

2-5mins

Question 15

How often is the total tear volume replaced

Answer 15

5-6 mins

Question 16

How can you reduce risk of drug absorption via nasolacrimal system
and what is the disadvantage of your method

Answer 16

occlude the nasolacrimal duct

increases rate of systemic absorption via conj , limbal and episceral vessels

Question 17

State components involved in ophthalmic preparations

Answer 17

active ingredients 
vehicle its in 
preservatives
buffers
tonicity agents 
viscousity enhancing agents

Question 18

List different drug delivery systems

Answer 18

multidose dropper bottles/single dose applicators for AS
tubes for gels/ointments
solid delivery systems = collagent shields,SCL,nafl
continuous flow devices
periocular inj
direct ocular inj
- intravitreal and intracameral

Question 19

Sate a disadvantage of using preservatives in drug

Answer 19

some pts may develop sensitivity and have reactions to it

Question 20

Multidose preservative free drugs have two systems - explain what each of them are

Answer 20

1. ABAKS system
2. 2 FILTER IN applicator that prevents ingress of infective organisms
3. Monodose system
   - has a mechanical system used to expel only one drop of the drug n prevents ingress of infective organisms

Question 21

Using a prodrug can be useful when

Answer 21

• active form would penetrate poorly through ocular structures
• active form produces affects around the eyes ( allergy)

Question 22

State three properties of ophthalmic preparations

Answer 22

pH
Tonicity
Viscosity

Question 23

Discuss what you know abou the pH of ophthalmic drugs

Answer 23

Drugs need to be close in Ph of the tear film which is approx 7.35
drugs with higher or lower ph will cause stinging
Buffers are used ot control pH

Question 24

Give examples of Buffers

Answer 24

acetic acid
boric acid
potassium bicarbonate
sodium citrate n phosphate

Question 25

Discuss what you know about the tonocity of ophthalmic drugs

Answer 25

cornea - semi permeable membrane draw fluid out and inot cornea depending on tonicity hypertonic = higher ion conc , outflow of fluid hypotonic - lower ion conc - oedema

Question 26

Discuss what you know about the viscosity of ophthalmic drugs

Answer 26

high V of drugs - increased contact with eye , increases chances of absorption but interferes with vision V is controlled by vehicle its in examples methylcellulose ,carbomers

Question 27

increase in corneal absorption by factor of two is achieved

Answer 27

by 100 fold increase in viscosity

Question 28

what would be the ideal viscosity of the following diagnostic therapeutic day therapeutic night

Answer 28

1. low V , short duration contact with eye , minima absorption of drug 2. low V , good vision 3. high V , smeary vision , high contact time with eye

Question 29

What would you find on the packaging of a drug

Answer 29

``` name conc BN ED DOM storage Req Manafactures details Legal Class Seal ```

Question 30

List sterilisation methods of ophthalmic drugs

Answer 30

``` Heat Autoclaving Filtration Ultrasound Ionising radiation UV light ```

Question 31

Heat sterilisation is useful for which type of drugs

Answer 31

thermostable drugs - don't get destroyed by high temp

Question 32

What temp is needed kill viruses using heat

Answer 32

60o

Question 33

Autoclaving is

Answer 33

heating drug in steam environment | 121 degrees for 15 mins

Question 34

Filtration of a drug is done using

Answer 34

a 0.22 mm filter retains bacteria not viruses

Question 35

Ultrasound is effective against

Answer 35

bacteria

Question 36

Ionising radiation is useful for

Answer 36

drug filter papers

Question 37

UV light useful for

Answer 37

killing bacteria

Question 38

Purpose of preservative is to

Answer 38

defend from microbial contamination once package is opened

Question 39

State name of commonly used preservative and its function

Answer 39

Benzalkonium chloride (BAK) A quaternary ammonium compound Disrupts bacterial cell membranes

Question 40

what enhances the effect of BAK

Answer 40

chelating agent called EDTA

Question 41

Discuss what you know about the minims Ophthamic preparations

Answer 41

Single use - contain half ml of drugs = 12 drops preservative free supplied in box of 20 sterlised via autoclaving at 115 for 30 mins

Question 42

explain the process of instilliation of minims

Answer 42

Patient tips head backward slightly Patient directs gaze upwards (~45º) Pull down lower eyelid Expose inferior fornix Apply one drop to the inferior fornix Avoid contact with the cornea Release eyelid. Ask patient to gently close eye Occlude lacrimal duct when using drugs with risk of adverse systemic response

Question 43

When using a drug on a pt what is important to consider

Answer 43

``` Four D drug date dose dispose ```

Question 44

Ideal storage for minims

Answer 44

cool dry place less than 25 degrees | some may need fridge 2-8deg

Question 45

give examples of drugs that need to be stored in the fridge

Answer 45

minims proxymetacaine | minims chloramphenicol