Pharmaceutical Excipients Overview

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Questions and Answers

What advantage does anhydrous lactose have over hydrous lactose?

It has a faster drug release rate.

It is more effective as a binder.

It does not undergo discoloration when aged. (correct)

It has a lower cost than hydrous lactose.

What happens to anhydrous lactose when exposed to elevated humidity?

It converts into its hydrous form. (correct)

It does not change at all.

It reacts with drugs.

It becomes less soluble.

When is hydrous starch typically used in tablet formulation?

During wet granulation to improve binding. (correct)

To enhance the disintegration time of tablets.

As a binder when added as a dry powder.

As a diluent when mixed with antibiotics.

What is one disadvantage of using the hydrous form of lactose in formulations?

It undergoes discoloration with certain compounds. Signup and view all the answers

For what purpose can dextrose be used in formulations?

To minimize discoloration when used with alkaline compounds. Signup and view all the answers

What role does starch play when it is added dry at the beginning of the procedure?

It functions as a diluent. Signup and view all the answers

Which of the following options describes the optimal use of starch in formulations?

As a disintegrant when added after granulation. Signup and view all the answers

What is the potential issue caused by using talc in formulations containing drugs sensitive to iron?

Talc can catalyze drug breakdown. Signup and view all the answers

Which of the following processes does NOT belong to tablet formulation?

Filtration Signup and view all the answers

What can happen if under-mixing occurs during tablet formulation?

Impaired content uniformity. Signup and view all the answers

What is one advantage of granules compared to individual fine powder ingredients?

Granules have better compressibility. Signup and view all the answers

Which statement best describes wet granulation in tablet manufacturing?

It typically provides easier control over the process. Signup and view all the answers

What is a primary advantage of mannitol in chewable tablets?

It has a sweet taste and provides a pleasant mouthfeel. Signup and view all the answers

Which of the following is an advantage of using microcrystalline cellulose as a diluent?

It has low moisture content and high purity. Signup and view all the answers

What is a limitation associated with natural gums such as acacia and tragacanth as binders?

They can easily be contaminated by bacteria. Signup and view all the answers

Why is gelatin often preferred over natural gums as a binder?

It is easier to prepare in solution and has consistent performance. Signup and view all the answers

What is a significant characteristic of starch when used as a binder?

It is converted into dextrin and glucose when hydrated and heated. Signup and view all the answers

How does mannitol affect the flowability of formulations?

It negatively impacts flowability and requires high lubricant levels. Signup and view all the answers

What defines the compressibility of Avicel-containing tablets?

Short disintegration time and high hardness. Signup and view all the answers

Which factor is a disadvantage of using natural gums in formulations?

Their performance can be inconsistent based on their source. Signup and view all the answers

What is a disadvantage of mannitol's expense in pharmaceutical applications?

It may make the overall formulation cost prohibitive. Signup and view all the answers

What is one significant characteristic of croscarmellose sodium compared to starch in acidic media?

Croscarmellose sodium swells to 900% of its original volume. Signup and view all the answers

Which statement accurately describes the function of lubricants in tablet manufacturing?

They reduce friction between the tablet and die cavity walls. Signup and view all the answers

What is a potential disadvantage of using liquid lubricants, such as mineral oils?

They might produce oil spots that can affect tablet appearance. Signup and view all the answers

What mechanism allows lubricants to reduce friction during tablet ejection?

Fluid lubrication forming a thin film. Signup and view all the answers

How do antiadherents function in tablet formulation?

They reduce stickiness of granules to the die walls. Signup and view all the answers

Which of the following is not a known advantage of lubricants?

Enhancing dissolution rates. Signup and view all the answers

What percentage of swelling is typical for starch in acidic media?

25% Signup and view all the answers

Why are glidants used in tablet formulation?

To promote the flow of powders by reducing friction. Signup and view all the answers

Which of the following is true about crospovidone (Kollidon CL)?

It acts as a disintegrant with potent swelling properties. Signup and view all the answers

What role does a glidant play when added to a tablet formulation?

Facilitates better flow of granules during processing. Signup and view all the answers

What is the primary purpose of boundary lubrication in tablet formulations?

To prevent sticking of the tablet to the die Signup and view all the answers

Why should lubricants be added last, right before compression?

To ensure they coat the granule surfaces rather than penetrating inside Signup and view all the answers

What is the consequence of using more than 1% lubricant in a formulation?

It may lower the dissolution rate and alter bioavailability Signup and view all the answers

What is the recommended particle size for effective lubricants in tablet formulations?

200 mesh or finer Signup and view all the answers

What impact does over-mixing have on the efficacy of lubricants?

It causes lubricant penetration from the surface to the core Signup and view all the answers

What is the maximum mixing time recommended for adding lubricants to a tablet formulation?

2-5 minutes Signup and view all the answers

Which lubricant is NOT suitable for use with alkaline drugs?

Stearic acid Signup and view all the answers

What happens at high mixing rates when incorporating lubricants?

They cause lubricant penetration into the core of the mixture Signup and view all the answers

Which lubricant is considered inert and has good lubricating properties?

Zinc stearate Signup and view all the answers

What critical characteristic must lubricants possess to be effective in formulations?

Small particle size Signup and view all the answers

Study Notes

Excipients

Excipients are non-drug materials in a formula
Excipients are crucial for several reasons
Improve patient compliance (color, flavor, sweeteners)
Increase dosage form stability (antioxidants, preservatives)
Increase dose accuracy (diluents, fillers)
Act as process aids (binders, lubricants)
Improve and control drug release (disintegrants, coating agents)

Types of Excipients

Diluents (Fillers): lactose, starch, microcrystalline cellulose
Binders (Granulating Agents): starch, acacia, gelatin
Disintegrants: starch, super disintegrant
Lubricant, Antiadherent, Glidants: magnesium stearate, stearic acid

Diluents (Fillers)

Used to bulk up tablets when the drug alone isn't enough.
Sometimes not needed if the drug has good compressibility.
Round tablets are typically 5-13mm; smaller or larger tablets can be difficult to handle or swallow.
Diluents improve tablet properties like cohesion and flow.

Lactose

Widely used diluents in tablet formulation
Doesn't react with most drugs.
Three forms: anhydrous, hydrous, spray-dried
Anhydrous is better for aging as it does not discolor (Maillard reaction).
Anhydrous can absorb moisture and turn into hydrous form in humid environments.
Hydrous form is often used with wet granulation.

Starch

Derived from corn, wheat, or potatoes
Used as diluent (50-60%), binder (2-10%), or disintegrant (5-20%) depending on the formula's needs.
Added as a powder or paste in specific stages of tablet production.

Other Diluents

Dextrose: Available as hydrous and anhydrous forms.
Can be used as a replacement for lactose to minimize discoloration with alkaline compounds
Mannitol: Used widely in chewable/orodispersible tablets due to its sweet taste, slow solubility and lack of hygroscopicity.
Expensive, poor flow, requires high lubricant level

Microcrystalline Cellulose

Often referred to as Avicel®
Multipurpose excipient used as a diluent and disintegrant
Inert, can be used with alkaline or acidic substances (no discoloration).
High purity and low moisture content
Directly compressible due to good compressibility and flowability
Avicel-containing tablets have short disintegration times, high hardness, low friability and low variation in weight.

Binders (Granulating Agents)

Bind particles together to form granules/compacts.
Include acacia, tragacanth, gelatin, starch -paste.
Acacia and tragacanth are natural gums and are more effective as solutions.
Gelatin is a synthetic protein, preferred over acacia and tragacanth.
Starch paste is a commonly used granulating agent.

Modified Natural Polymers

Common binders such as Alginates, methylcellulose (MC), ethyl cellulose (EC), hydroxypropyl cellulose (HPC) and hydroxypropyl methylcellulose (HPMC)
(Except for EC), used in powder form or as solutions.
HPC can be used in alcoholic solution.
EC is insoluble in water, used in alcoholic solution to prevent tablet disintegration.

Disintegrants

Oppose the effect of the tablet binder, and physical force (applied during compression).
Facilitate breakdown of tablets in GI fluids.
Example of disintegrating agents are starch, and super disintegrant.

Starch (Disintegrants)

Most widely used due to low cost.
Quick water uptake and swelling leads to tablet rupture.
Super disintegrants (Explotab®, croscarmellose sodium, crospovidone): powerful disintegrating agents
Used at ratios of 5-20% of the tablet weight.

Lubricants, Antiadherents and Glidants

Lubricants reduce friction during tablet ejection from the die cavity.
Antiadherents reduce sticking of granules to die walls.
Glidants promote granule flow by reducing friction between particles.
Lubricants help with production and may influence bioavailability.
Lubricants should be added to the surface of granules.
Small particle size 200 mesh, larger particle size decrease efficacy.
Mixing time (2-5 mins) and mixing rate (high mixing rate causes penetration and decreases efficacy) influence efficacy.
Magnesium or Calcium stearate is the most widely used lubricant.
Stearic acid is less effective than the salts, not used with alkaline drugs.
Zinc stearate is effective in direct compression and is inert.
Talc may also be used as a lubricant (contains iron so it has to be applied carefully).

Tablet Design and Formulation

Tablet formulation involves weighing, granulation(wet/dry granulation is used for wet granule process / dry granule process / direct compression) , mixing, and compression.
A crucial stage of the manufacturing process, uniform distribution (mixing), and adequate (appropriate/proper) distribution of lubricants is essential.

Mixing

A critical step in tablet formulation.
Uniform distribution of tablet constituents.
Allows proper distribution of lubricants.
Undermixing leads to impaired content uniformity, poor flow properties
Overmixing leads to problems in the tablet manufacturing process such as poor flow properties due to lubricants entering into the tablet granules.

Granulation

Addresses flowability and compressibility issues common in fine powder drugs.
Granules have better flowability and compressibility than individual ingredients.
Ensures the consistent distribution of API (active pharmaceutical ingredient) in the formulation.

Wet Granulation

Common method using liquid binder.
More steps; better control over the process.
Involves mixing active ingredients, excipients and a liquid binder , followed by drying and milling to achieve the desired size.

Dry Granulation

Used when granulating solutions are not suitable, especially with heat-sensitive drugs.
Involves mixing drug powder, inactive ingredients and passing them through a roller, creating slugs, then milling/screening to the required size.

Direct Compression

A method used when the drug and excipients are suitable for direct compression.
Avoids a granulation step.
Advantages include simplicity, lower labor and risk of ingredient deterioration.
Requires certain properties in the active ingredient and/or excipients (crystalline nature and easy compressibility), limitation arises if intermolecular interaction is weak.

Compression

Final step; requires careful evaluation of factors beyond this overview.

Tablet Compression Machine

Comprises of a hopper, dies, punches, cam tracks.
Also includes auxiliary equipment, such as automatic feeders and dusters (beyond this scope)

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Description

This quiz provides an overview of pharmaceutical excipients, detailing their types and roles in drug formulations. Learn about diluents, binders, disintegrants, and other crucial components that improve patient compliance and drug stability. Test your knowledge on how excipients contribute to effective drug delivery.