Tablet quality

Question 1

What are the different chemical, biological, and physical ways that a tablet can be evaluated?

Answer 1

chemical: assay and stability
biological: bioavailability, drug performance
physical: dimensions, weight, friability, disintegration, release profile

Question 2

What is the test for tablet dimension?

Answer 2

Measure 20 tablets and ensure their standard length doesn’t deviate from the average length by more than 5%.

Question 3

What are the possible causes of variation in tablet dimension?

Answer 3

• compression properties

- die fill: raw materials, punch length, machine operation, granulation properties

Question 4

What is the test for tablet weight and its purpose?

Answer 4

• compliance will ensure uniformity of weight and reduce the likelihood of tablet cracking.
• weigh 20 tablets individually and take the average mass, ensure that it conforms to BP regulations.
• weight of the content inside: capsule-empty shell

Question 5

What are reasons for the variation of tablet weight?

Answer 5

• dimensions of die cavity
• amount of fill
• density of tablet material

Question 6

What is the test for friability and its purpose?

Answer 6

• compliance helps to ensure that tablets can withstand the mechanical shocks and abrasion during the manufacturing, transportation and packaging processes.
• Drugs are rolled in a rotating drum together with beads for a specified amount of time.
• When they are taken out, their weight loss should not be greater than 1%.

Question 7

What happens if tablets fail the first round of friability test?

Answer 7

• take 2 more readings and take the average of the 3 tests.

- the average should not exceed 1% change in weight.

Question 8

What is the hardness test and its purpose?

Answer 8

• compliance helps to ensure tablet does not succumb easily to external penetration and indentation from probe.
• measure the diameter of the tablet, or parallel to the longest axis of the tablet for more information on its weakest point.
• calculate tablet strength with equation.
• measure the hardness of 10 tablets and take the minimum, maximum and average force, in Newtons.

Question 9

What is the disintegration test?

Answer 9

Using the disc method, place 1 tablet into each of the 10 tubes that have a film at the bottom.
Maintain temperature for 35-39 degree celsius for 15 minutes.
At the end of the specified time, all the tablets should have dissolved.
If one or two tablets fail, repeat with 12 more. To pass the test, at least 16 out of 18 of the tablets must dissolve.

Question 10

What are the advantages of release testing?

Answer 10

• optimise the manufacturing process

- ensure that tablets of sufficiently good quality are produced.

Question 11

What are the techniques used for in-vitro dissolution of conventional solid dosage forms?

Answer 11

• basket method
• paddle method
• reciprocating cylinder method
• flow-through cell

Question 12

How to use the basket and paddle method?

Answer 12

• Basket method: vessel contains a basket as a stirring element.
• Paddle method: vessel contains a paddle formed from a blade and a shaft as its stirring element.
• Maintain temperature in water bath at 37+/- 0.5 degree celsius.
• Take out concentrations of the samples at the various timepoints and plot a graph of % concentration of the drug over time.

Question 13

How to use the reciprocating cylinder method?

Answer 13

• Use 6 rotating cylinders, each with a different pH medium inside.
• Place a dosage form into each of the cylinders and operate the apparatus.
• Distance moved from the upward and downward stroke of the apparatus should cover 9.9-10.1cm.
• Throughout the specified duration, cylinders are kept in a water bath of 37 +/- 0.5 degree celsius.
• Withdraw samples of the drug at certain timepoints and measure their concentrations and plot a graph of % concentration of the drug over time.

Question 14

How to use the flow-through cell method?

Answer 14

Flow-through cell comprises:

• a reservoir filled with the dissolution medium
• a pump
• thermostatically controlled flow-through cell
• water bath

Beads are placed on top of the flow-through cell, and drugs are placed on top of the beads. Water bath controls the temperature of the cell at around 37 +/- 0.5 degree celsius.

Pump dissolution medium to the bottom of the cell to obtain the flow rate specified, and collect the eluate at fractions at specific timepoints.

Question 15

How can one calculate the rate of release of the drug per unit time?

Answer 15

dm/dt = AD/L (Cs-Cb)