Tablets

Question 1

What is a tablet?

Answer 1

solid preperation which contains a single dose of one or more active ingredient.

Question 2

Advantages of tablets

Answer 2

-good patient compliance
-convenient
-accurate dosing
-chemical, physical and microbial stability
-cheap, robust, elegent

Question 3

disadvantages of tablets

Answer 3

-generally systematic delivery
-poor bioavailability
-must be swallowed
-first pass metabolism / GI track instability
-local irritation -GI mucosa

Question 4

Immediate release tablet types

Answer 4

disintegrating
chewable
effervescent
sublingual / buccal

Question 5

modified release tablet types

Answer 5

-extended release - released slowly at a constant rate
-pulsatile release - released in two or more pulses
-delayed release - released some time after administration

Question 6

disintegrating tablets

Answer 6

-Drug release: disintegration>dissolution>absorption
-disintegration rate: dependent on several formulation and production factors
-dissolution rate: limited by drug factors such as solubility and particle size
-absorption rate: lipophilicity
examples: paracetamol, ibuprofen

Question 7

chewable tablets

Answer 7

-disintegrate in mouth
-mechanical disintegraiton - no disintegrant
-drug dissolves in stomach
-rapid effect, no water requied
-for patients with difficulty swallowing
-flavourings/colourings commonly used
-examples: vitamins, gaviscon

Question 8

effervescent tablets

Answer 8

-dropped into glass of water
releases co2, fascilitating disintegration and dissolution
rapid drug action
examples: analgesics, vitamins

Question 9

compressed lozenges

Answer 9

-dissolves in saliva
-slow drug release - no disintegrant
-systematic and local delivery
-filler and binder - water soluble and acceptable taste eg. carbohydrates and sugar
-colouring, flavouring
-high pressure - increased hardness and low porosity
eg. strepslis, nicotine

Question 10

sublingual and buccal tablets

Answer 10

sublingual - tablet placed under tongue
buccal - tablet placed in =side of cheek
-systematic delivery avoiding first pass metabolism / Gi tract
-rapid drug release - small, porous, completely disintegrate and dissolve
-buccal modified release - slow release (1-2 hours)
eg. nitroglycerin, loratadine, nicotinell

Question 11

excipients

Answer 11

-ensures the produciton process runs efficiently and produces tablets of a required standard

Question 12

types of excipients

Answer 12

Question 13

procceses: direct compression
advantages and disadvantages

Answer 13

mixing > tabletting
advantages:
reduction in manufacture time and costs
faster drug dissolution
disadvantages: specialist fillers/binders required
powder must have good flow properties
powder segregation
poor drug compactability
poor colour uniformity

Question 14

processes: granulation
advantages and disadvantages

Answer 14

mixing>agglomeration>drying>milling>mixing>tabletting

Advantages:
-improves homogeniety, prevents powder segregation
-improves powder flow properties
-increases compactability
-increases bulk density
-colour homogeniety

diadvantages:
-increase in production time/costs
may cause drug hydrolysis

Question 15

compaction

Answer 15

forcing particles into close proximity to eachother by confined compression.

Question 16

single punch tablet press

Answer 16

output upto 200 tablets/min - production of small batches
eg. during formulation development and clinical trials

Question 17

rotary tablet press

Answer 17

> 10,000 tablets/min
multiple sets of tooling
powder flows by gravity from the hopper onto the die table and feed into the die by powder feeder, punches compress powder and feeder knocks tablet to eject

Question 18

technical problems during tabletting

Answer 18

weight/dose variations
low mechanical strength
capping
lamination
sticking - powder stinks to surface of punch
picking - particles stick to letts/logos of the punch
chipping

Question 19

Reasons for tablet coating

Answer 19

-protect the dryg
-mask the taste
-ease of swallowing
-improve appearance
-rapid identification
-ease of handling
-increase bulk
-modified release characteristics

Question 20

3 types of tablet coating

Answer 20

-film
-sugar
-compression

Question 21

Film coating

Answer 21

-polymers, plasticizers, colurants sprayed onto rotating tablets / multiparticulates (MR)

Immediate (non functional)
water soluble, eg. hpmc, pvp

MR (functional)
pH 5-6 eg. ethyl cellulose (EC)

Question 22

sugar coating

Answer 22

sucrosed based syrup - sugar coating pan
(6 stages)
sealing, sub coating, smoothing, coluring, polishing, printing)
-Readily water soluble - disintegrate
-immediate release

Question 23

compression coating

Answer 23

less common
complex - compaction of granular particles around tablet core in tablet machine

Question 24

Tablet attributes

Answer 24

-contains correct dose
-consistent weight, size and appearence
-drug release controlled and reproduceable
-have sufficient mechanical strength
-physically, chemically and microbiologically stable
-formulated for patient acceptence
packaged approprietely

Question 25

determination of constant drug dose content

Answer 25

-weigh individually 20 tablets at random and determine average mass
-not more than 2 individual tablets deviate from the average mass by more than the percentage deviation shown, and none deviates more than twice the percentage
-accuracy dependednt upon % for drug content - higher drug content more accurate

Question 26

mimic forced encountered during handling

Answer 26

-tablets must resist friability to ensure doese and appearence is maintained