Psychiatry II

Question 1

What are the factors required of patients (in addition to drug efficacy) to have successful pharmacotherapy? (3 points)

Answer 1

• optimal dosage forms
• enhanced compliance
• reduction of side effects

Question 2

Why is psychotherapy challenging? (4 points)

Answer 2

• Patient may be poorly adherent to medication
• This may be due to px being unable or unwilling to take medications
• This results in therapeutic failure
• This can cause harm to the patient and harm to the public.

Question 3

How is compliance dealt with?

Answer 3

often via different formulations

Question 4

What are the different formulations of psychotherapy? (4 points)

Answer 4

• depot injections
• CR oral device
• rapidly dissolving tablets
• transdermal patches

Question 5

When are depot injections used? (2 points)

Answer 5

• patient may be uncooperative or incompetent

- available in oily and matrix injections

Question 6

When are CR oral device medications ideal?

Answer 6

-patient is cooperative and/or has limited competence

Question 7

When are rapidly dissolving tablets used?

Answer 7

-patient is unable to swallow or uncooperative

Question 8

When are transdermal patches used?

Answer 8

-when the patient is cooperative but has limited competence.

Question 9

How does a depot formulation work? (2 points)

Answer 9

• depot is released in aqueous tissues

- drug partitions from oily sollution into aqueous tissues in accordance with o/w partition coefficient of the drug

Question 10

What are the advantages of making a depot suspension? (3 points)

Answer 10

• maintains saturated oily solution
• achieves zero order release
• drug has prolonged duration of action due to dissolution, partition and absorption processes

Question 11

What is an example of a depot suspension? (3 points)

Answer 11

• depo provera injectable suspension
• contains medroxyprogesterone acetate 150mg
• 1 injection every 12-13 weeks

Question 12

What are the advantages of a gel depot formulation? (2 points)

Answer 12

• liquid in the syringe but gelates in response to pH or temperature
• in gel form the release is slower

Question 13

What is an example of a depot gel formulation? (3 points)

Answer 13

-Eligard contains a LHRH antagonist (orally active peptide)
-injected as liquid but solidifies in situ
-biodegrades causing continuous release
previously microsphere intramuscular injection often therapeutically inadequate

Question 14

What are the limitations with risperidone oily suspension depot? (4 points)

Answer 14

• risperidone oily suspension requires 1 injection every 2 weeks
• there is a 3 week lag for effect
• takes 4-6 weeks to reach Cmax
• takes 7-8 weeks to be completely eliminated

Question 15

how can the risperidone depot be improved?

Answer 15

-adding an immediate release formulation with the depot to get rid of the lag time required.

Question 16

How do the oral CR formulations work? (4 points)

Answer 16

• Drug is contained in a membrane controlled matrix
• as it is ingested, fluid enters via an orfice which increases pressure inside the formulation
• pressure builds and slowly releases the drug
• follows zero order kinetics but is slow to start.

Question 17

What is an example of oral CR formulation? (6 points)

Answer 17

• OROS Concerta
• two drug reservoirs with a push compartment are contained in a MPH overcoat. When exposed to aqueous environment, releases 22% of dose in first hour
• Laser drilled hole in drug reservoir 1 allows drug to escape under hydrostatic pressure
• Semi permeable membrane between DR1 and 2 allows DR1 to function as conventional osmotic pump
• push compartment helps to release drug from DR2
• tablets cannot be halved, crushed or chewed.

Question 18

What is an example of a rapidly dissolving tablet? (6 points)

Answer 18

• Zyprexa Zydis wafers (olanzapine)
• Freeze dried rapidly dispersing preparation
• can be placed in mouth to dissolve or dispersed in water or other beverages
• avoid cola beverages
• consider taste, contains aspartame
• bioequivalent to Zyprexa coated tablets. Has similar rate and extent of absorption.

Question 19

What is an example of a transdermal drug for psychotherapy? (6 points)

Answer 19

• transdermal haloperidol
• theoretically can minimise peak concentrations
• drug is dispersed in glycerol and PVA in water
• Eudagrit NE 30D added to make the solution solidify on removal of water
• Reduced Cmax but longer Tmax
• C max below toxic levels but high enough to be effective for more than 24 hours.

Question 20

What is eudagrit NE 30D?

Answer 20

-insoluble, inert polymer

Question 21

What is carbamazepine? (5 points)

Answer 21

• antiepileptic
• available as syrup (suspension), conventional tablets and CR tablets
• Syrup: Cmax 2 hours
• Conventional tablets Cmax 12 hours
• CR tablets Cmax 24 hours

Question 22

What are CR carbamazepine tablets designed for? (7 points)

Answer 22

• twice daily admin
• can be divided but parts must be swallowed whole and notchewed
• Cmax within 24 hours
• 25% lower peak concentrations than other formulations
• 15% lower bioavailability than other tablets but C min at Css is not significantly lower
• fluctuations and SE reduced.
• better therapeutic cover

Question 23

What is zuclopenthixol? (5 points)

Answer 23

• neuroleptic agent
• available as depot oily injections delivered IM
• combination of acetate (Cmax 24-36 hours) and decanoate (Cmax 3-7 days)
• decanoate is essentially a prodrug
• achieves sustained release and gets rid of lag time