Psychiatry II Flashcards
What are the factors required of patients (in addition to drug efficacy) to have successful pharmacotherapy? (3 points)
- optimal dosage forms
- enhanced compliance
- reduction of side effects
Why is psychotherapy challenging? (4 points)
- 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.
How is compliance dealt with?
often via different formulations
What are the different formulations of psychotherapy? (4 points)
- depot injections
- CR oral device
- rapidly dissolving tablets
- transdermal patches
When are depot injections used? (2 points)
- patient may be uncooperative or incompetent
- available in oily and matrix injections
When are CR oral device medications ideal?
-patient is cooperative and/or has limited competence
When are rapidly dissolving tablets used?
-patient is unable to swallow or uncooperative
When are transdermal patches used?
-when the patient is cooperative but has limited competence.
How does a depot formulation work? (2 points)
- depot is released in aqueous tissues
- drug partitions from oily sollution into aqueous tissues in accordance with o/w partition coefficient of the drug
What are the advantages of making a depot suspension? (3 points)
- maintains saturated oily solution
- achieves zero order release
- drug has prolonged duration of action due to dissolution, partition and absorption processes
What is an example of a depot suspension? (3 points)
- depo provera injectable suspension
- contains medroxyprogesterone acetate 150mg
- 1 injection every 12-13 weeks
What are the advantages of a gel depot formulation? (2 points)
- liquid in the syringe but gelates in response to pH or temperature
- in gel form the release is slower
What is an example of a depot gel formulation? (3 points)
-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
What are the limitations with risperidone oily suspension depot? (4 points)
- 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
how can the risperidone depot be improved?
-adding an immediate release formulation with the depot to get rid of the lag time required.
How do the oral CR formulations work? (4 points)
- 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.
What is an example of oral CR formulation? (6 points)
- 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.
What is an example of a rapidly dissolving tablet? (6 points)
- 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.
What is an example of a transdermal drug for psychotherapy? (6 points)
- 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.
What is eudagrit NE 30D?
-insoluble, inert polymer
What is carbamazepine? (5 points)
- antiepileptic
- available as syrup (suspension), conventional tablets and CR tablets
- Syrup: Cmax 2 hours
- Conventional tablets Cmax 12 hours
- CR tablets Cmax 24 hours
What are CR carbamazepine tablets designed for? (7 points)
- 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
What is zuclopenthixol? (5 points)
- 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
