pharmaceutical Technology-2

  

(a) What are the reasons for tablet coating?

 Given below the major reason for tablet coating ---

 

1.   To protect the ingredient from environment particularly from light, air and moisture.

2.   To mask the disagreeable taste, odor and color of the drug.

3.   To provide physical and chemical protection to the drug.

4.   To control the release profile of the drug form the tablet.

5.   To protect the drug form the gastric environment of the stomach, or to escape the irritating action of the drug to the stomach by using an acid resistant enteric coating.

6.   To incorporate another drug or adjuvant in a coating to avoid chemical incompatibilities or to provide sequential drug release.

7.   To improve the pharmaceutical elegance by the use of special color coating.

8.   To facilitate handling especially during packaging and filling.

9.   To improve product identity by the manufacturer.

(b) What coating is needed for a tablet to make it waterproof?

Sugar coating is an aquous process during which the tablet core is thoroughly wetted by sugar solution; so sealing is the mandatory step in sugar coating. Sealing is also called water proofing. It is essential for separating the tablet ingredient and water in order to assure the good product stability.

The necessity of sealing is also strengthening the tablet core. Sealents are usually the alcoholic solution of resin. Example: Shellac, Zein, CAP, PAP.

Shellac: It is a resinous secretion of lac insect (Laccifer lacca). Shellac is an effective sealent but tablet disintegration and dissolution time tend to lengthen on aging because of polymerization of Shellac.

Zein: Alcohol soluble protein derivative obtained from corn.

PAP & CAP: Cellulose acetate phthalate and polyvinyl acetate phthalate used enteric coated tablet.

 

2(a) Discuss about various processing problems encountered in the preparation of  tablet?

In the process of developing formulation and in routine manufacturing of tablet, various problems occur. Sometimes the source of problem is ---

•        Formulation problem.

•       Faults in compression equipment.

•       Sometimes combination of above two

The formulation defects of tablets are as follows ---

1.   Capping and lamination.

2.   Picking and sticking.

3.   Mottling.

4.   Weight variation.

5.   Hardness variation.

6.   Double impression

(b) What are the similarities and dissimilarities between compression coating  and sugar coating?

Given below the similarities and dissimilarities between compression coating  and sugar coating: 

 

Dissimilar		Similar
compression coating	sugar coating
Used for heat sensitive drug.	Can not be use for heat sensitive drug.	But both form a coating on the tablet.
Final products are lighter, smaller, there by easier to swallow.	Final products are heavier..	Both coating increase he tablet’s mass.
Less coating materials are needed.	More coating materials are needed.	coating materials are needed for both types of coating.
Less expensive to package and shipment.	Relatively more expensive to package and shipment.	Both are expensive than uncoated tablet.
Process can be automated.	Process can be manual.	More coating steps than uncoated tablet.

What is the difference between sugar coating and film coating:

 

Sugar coating	Film coating
Sugar coating involves the deposition of sucrose solution onto the tablet.	Film coating involves the deposition of thin polymeric film.
Sugar coating is an oldest method.	It is newly developed method.
This process arrow in the middle of 19th century.	Film coated was first marketed by Abbott company in 1953.
The tablet appearance of sugar coating is rounded with high degree of polishing.	Film coated tablet are not usually as shiny as sugar coated tablet and it can retain the contour of original core.
In case of sugar coating (30-55) % of original weight of the tablet may increase.	Weight increase due to film coating is (2-3) %.
Logo or break line cannot appear through sugar coating.	Logo or break line can appear through sugar coating.
Considerable or special operator training is required for sugar coating.	This process lends itself automation and operator training is easy.
Sugar coating is a multistage process.	It is usually a single stage process.
Example: Sugar syrup, Zein, Shellac, Polymer (PEG, HPEC, HPMC) etc.	Example: Na-CMC, CAP, PAP, HPMCP, HPMC etc.

 

3(a)  Define granulation. Why it is necessary?

 

Granulation is the process in which powder particles are made to adhere to form larger particle or granule.

Necessities of granulation (Why granulation is necessary?)

 Granulation is necessary because ---

 

1.   Primarily to prevent the segregation on the powder mix.

2.   To improve the flow property.

3.   To enhance the compression characteristics.

4.   The granulation of toxic material will reduce the hazard of the granulation.

5.   Materials are slightly hydroscopic may adhere in the form of a cake if stored as a powder. Granulation can prevent the formation of cake.

6.   Granules being denser than the parent powder mix occur less volume per weight. They are therefore more convenient for storage or shipment.

 

Why disintegrants are incorporated in two steps during tablet manufacturing?

Illustrate Air Suspension method for tablet coating.

What is the Necessities of excipients?

Excipients plays a wide variety of functions in pharmaceutical dosage form including ---

•       They provide the drug products delivery system. They transport the active drug to the site in the body where the drug is intended to exert its action.

•       Excipients will keep the drug from being released too early in assimilation process in places where it could damage tender tissue and create gastric irritation or stomach upset.

•       Some excipients help the drug to disintegrate into particles small enough to reach the blood stream more quickly and effectively at the time of use.

•       Some excipients modulate stability and bioavailability of API_S (Active pharmaceutical ingredients).

•       Helping the active ingredient to maintain preferred polymorphic forms or conformations.

•       Excipients are used to maintain the pH or osmolarity of liquid formulation.

•       Some excipients are used to aid the identification of drug product.

•       Some are important in the formulation of drug simply to make the product taste and look better which improved patient’s compliance especially in children.

•       In many products excipients make the bulk of the dosage form.

5(a) Why smoothing step in sugar coating is alternatively named syruping?

Syruping or smoothing: The purpose of this step is to cover and fill in the imperfection on the tablet surface caused by the sub coating step. Smoothing usually is accomplished by the successive application of dilute syrup, often the smoothy syrup contain a few percentage of Titanium Dioxide as a opacifier.

 

(b) Mention the common problems associated with sugar coated tablet .

 

Problems/defects of sugar coating tablet:

1.   Chipping of the coating tablet,

2.   Cracking,

3.   Soft core due to non-drying coating,

4.   Winning or the buildup multiple,

5.   Mottling,

6.   Blooming or sweating,

7.   Marbeling.

7.   Diagrammatically represent the most popular technique of coating.

Film coating involves the deposition, usually by a spraying method, of a thin polymer formulation surrounding a tablet. Film coating is newly developed method. Film coating tablet was first marketed in 1953 by Abbott Company. Film coating is the most popular technique and virtually all new coated products introduced to the market are film coated.

Film coated tablets are usually as shiny as sugar coated tablet and it retain the content of original core. Weight increases due to the film coating is 2-3% that is negligible. It is possible to appear original core. This process lends itself to automation and operator training is easier. Film coating is usually a single stage process. Film coated tablet: The deposition of thin membrane which consists of polymer (thickness 20-200µ) plasticizer & their derivatives.

 

Mechanism of film coating: Film formulation generally comprise in 5 steps:

•       Spraying of coating,

•       Deposition of droplets over tablet surface,

•       Coalescence of polymer droplet,

•       Removal of solvent & formulation of film over the surface,

•       Further removal of solvent drying & final formation of rigid film over tablet.