Tablets (Pharmaceutics)

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Tablets V V S Narayana Reddy Karri Lecturer Dept of Pharmaceutics JSS College of Pharmacy, Ootacamund ( JSS University, Mysuru ) Rocklands Udhagamandalam.


Contents Introduction Advantages and disadvantages Types of tablets Fine powder Vs. Granules Excipients used in formulation of tablets Manufacturing of compressed tablets Preparation of granules for compression Compression of Granules into tablets Coating of tablets Quality control of tablets Manufacturing defects in tablets Evaluation of tablets

1. Introduction:

1. Introduction solubilize Dissolution Diffusion Disintegration

Punches and Dies:

Punches and Dies


Definition Tablets are the solid dosage form containing medicament/medicaments , usually circular in shape and may be flat or biconvex . Tablets are prepared by compression method and hence called the “compressed tablets”

2. Advantages and Disadvantages:

2. Advantages and Disadvantages Advantages Easy to be administered Easy to be dispensed More stable dosage form Bitter and nauseous drugs can be given easily in dosage form after giving a suitable coating to the tablets They are light and most compact of all dosage forms They are economical They have long expiry period due to lower moisture content Disadvantages Bitter tasting drugs, drugs sensitive to oxygen may require extra coating which may increase the cost of the finished tablets. Tablets cannot be used in emergency cases Bioavailability of some drugs may be low due to poor absorption from the gastric GIT.

3. Types of tablets (According to route of administration):

3. Types of tablets (According to route of administration) Tablets ingested orally Compressed tablets Multiple compressed tablets Multilayered tablets Sustained action tablets Enteric coated tablets Sugar coated tablets Film coated tablets Chewable tablets Tablets used in the oral cavity Buccal tablets Sublingual tablets Lozenge tablets Dental cores Tablets administered by other routes Implantation tablets Vaginal tablets Tablets used to prepare solutions Effervescent tablets Dispensing tablets Hypodermic tablets Tablet triturates

A. Tablets ingested orally:

A. Tablets ingested orally Compressed tablets These are uncoated and made by compression of granules Used to provide rapid disintegration and drug release Multiple compressed tablets These tablets are prepared to separate physically or chemically incompatible ingredients . Multilayered tablets These tablets consists of two or more layers materials compressed in the same tablet. These tablets are also prepared to separate the physically incompatible material. Sustained action tablets These tablets are taken orally release the medicament in a sufficient quantity when required to maintain the maximum effective concentration of the drug in the blood stream through out the period of time.

A. Tablets ingested orally..:

A. Tablets ingested orally.. Enteric coated tablets These are designed to bypass the stomach and get disintegrated in the intestine only Sugar coated tablets These tablets containing a sugar coat to mask the bitter and unpleasant odour and taste of the medicament. Film coated tablets These tablets contain film coating of some polymer which protects the medicament from atmospheric effects . Chewable tablets These tablets are chewed in the mouth and broken in to small pieces. In this way, the disintegration time is reduced and absorption of medicament is increased .

B. Tablets used in oral cavity:

B. Tablets used in oral cavity Buccal tablets These tablets are placed in buccal pouch or between gums and lips where they dissolved or disintegrate slowly and absorbed in to blood without passing GIT Sublingual Tablets These tablets are placed under the tongue where they dissolved or disintegrate slowly and absorbed in to blood without passing GIT Lozenge tablets These tablets are designed to exert a local action in the mouth or throat . These tablets are commonly used to treat sore throat or to control coughing in common cold. Dental cones These are minor tablets meant for placing in empty sockets of teeth after tooth extraction . They prevent multiplication of bacteria in the socket after tooth removal

C. Tablets administered by other routes:

C. Tablets administered by other routes Implantation tablets These tablets are placed under the skin or inserted subcutaneously by minor surgery These tablets must be sterile Implants are used to administer some hormones Vaginal tablets These tablets are used to release antibacterial agents, antispetics etc ., to treat vaginal infections

D. Tablets used to prepare solutions:

D. Tablets used to prepare solutions Effervescent Tablets These tablets when added in water produce effervescence . So they dissolved rapidly in water due to the chemical reaction takes place between alkali bicarbonate and citric acid or tartaric acid or both. Dispensing Tablets These tablets are intended to be added to a given volume of water to produce a solution of given concentration . Hypodermic Tablets These tablets are composed of one more drugs with readily soluble ingredients. These tablets are dissolved in sterile water or water for injection and administered by parenteral route . Tablets Triturates These are small tablets ( cylindrical shape ) contain a potent medicament with a diluent .

4. Powders Vs. Granules:

4. Powders Vs. Granules Powder Granules

4. Powders Vs. Granules:

4. Powders Vs. Granules S.N Fine Powder Granules 1. Fine powder does not flow freely in hoper hence they produces the tablets of irregular weight . Granules flow freely in hoper hence they produces the tablets of uniform weight. 2. In powders ingredients mixture the vibrations of tablet punching machine separates the powders of higher density from lower density . Granules may be bigger or smaller but are uniform in composition . The ingredients are bound together and cannot separate. 3. Air is imprisoned during compression and may cause tablet defects. Granules have more knitting power . Hence on compression the granules form solid tablet. 4. Fine powder tends to blow out of the die and causes sticking of machine. The granules being heavier , do not blow out of the die and therefore do not stick to the machine.

5. Excipients used in formulation of tablets:

5. Excipients used in formulation of tablets

5. Excipients used in formulation of tablets..:

a. Diluent It is needed when the quantity of medicament is very small (potent) and not possible to make a good tablets e.g. Lactose, sucrose, dextrose etc., b. Granulating Agent These are used to convert the fine powder into granules . Granulating agents provides sufficient moisture to convert powder into damp mass which was then passed through a sieve to produce granules. e.g. water, alcohol, starch etc., c. Binding agent These are used in granulation to provide strength to the granules , in order to keep intact the tablet after compression. e.g. gum acacia, gum tracaganth methyl cellulose etc., 5. Excipients used in formulation of tablets..

5. Excipients used in formulation of tablets..:

d. Disintegrating agent These substances are added in tablet formulation to ensure disintegration of tablets in to smaller particles . e.g. Sodium bicarbonate, citric acid and tartaric acid etc., e. Lubricants These added to improve the appearance of tablet, flow properties of granules and to prevent sticking the materials to the dies and punches. Lubricants : That act by reducing friction by interposing an intermediate layer between the tablet constituents and the die wall during compression and ejection. e.g. magnesium and calcium stearate etc., Glidants: They are added to the formulation to improve the flow properties of the material . e.g. talc Anti-adhesive agents: These prevent the sticking of tablet surface to dies and punches during compression. E.g. magnesium stearate and stearic acid. 5. Excipients used in formulation of tablets..

5. Excipients used in formulation of tablets..:

f. Adsorbing agents These substances are added to adsorb volatile oil , liquid extract etc., which are included in the formulation of tablets. E.g. kaolin and starch. e.g. Sodium bicarbonate, citric acid and tartaric acid etc., g. coloring, flavors and sweetening agents: Colors: To improve the elegance of the tablet Flavors: These are volatile substances added in lozenges and effervescent tablets . Sweetening agents: To improve the taste of the tablets . 5. Excipients used in formulation of tablets..

6. Manufacturing of Compressed tablets:

6. Manufacturing of Compressed tablets I. Preparation of granules for compression II. Compression of granules into tablets III. Coating of tablets IV. Quality control of tablets

Slide 20:

Weighing the ingredients Mixing the powder ingredients and excipients Converting the mixed ingredients in to granules If the medicament along with excipients are in powder form it cannot be compressed as such (ref: powder vs. granules), so it has to convert into granules Types (a) Moist granulation (b) Dry granulation and (c) Granulation by preliminary compression I. Preparation of granules for compression

Slide 21:

Moist granulation I. Preparation of granules for compression

Slide 22:

I. Preparation of granules for compression… C. Granulation by preliminary compression (slugging) Suitable for medicament which is unstable in presence of moisture . In this method the dry powder is compressed in to slugs . These slugs are broken onto small pieces and passed through sieve No. 20 and then compressed b. Dry granulation They are certain substances available in the form of granules having its binding property . Such medicaments are directly passed to sieve No.20 and then compressed.

Slide 23:

II. Compression of granules into tablets The various machines used for this purposes are: Single-punch tablet punching machine (hand operated) Multiple punch Rotatory tablet machine Dry coat tablet machine In all the tablet machines the compression is achieved by filling the required amount of granules into the dies and then compressing them in b/w the lower and upper punch . Single punching machine is used in small scale manufacturing and other are used in large scale manufacturing.

Slide 24:

II. Compression of granules into tablets… 1. Single Punch tablet Machine: Hopper shoe ( supply granules to dies ) Lower punch Upper punch Capacity regulator ( adjust lower punch to accommodate granules ) e. Ejection regulator ( adjust lower punch, its highest position equals to surface of die ) Die ( allows upper and lower punches to come and compress the granules ) g. Driving wheel (helps in movements of upper and lower punch as well hopper )

Slide 25:

II. Compression of granules into tablets… Working of tablet punching machine Upper punch rises and allows the hopper shoe to move over the die. Lower punch drops and the granules feed from the shoe into die. The shoe moves a side and the upper punch drops, thus compressing the tablets into granules. Upper punch rises and lower punch rises up to the surface of die to eject the tablet. The lower punch drops and cycle is restarted.

Slide 26:

II. Compression of granules into tablets… 2. Multi-punch tablet machine It has 2 to 12 dies on big platform and number of punches depends on number of dies. 3 . Rotary tablet machine It is used for large scale production . 1200 tablets are prepared in one min . Circular rotating head carrying a number of punches and dies assembles. Hopper is filled with granules. As machine starts the hopper delivers the granules to die via feed frame. These granules get compressed when upper and lower punches comes together.

Tablet Manufacturing Process:

Tablet Manufacturing Process

III. Coating of Tablets:

III. Coating of Tablets

Slide 29:

To mask unpleasant taste and odor of the drug . To provide physical and chemical protection to the drug . To improve the appearance of tablets . To produce the sustain release effect . To control release of drug from the tablet . To protect the drug from gastric environment of stomach . Why to coat tablet..?

Coating of tablets…:

Coating of tablets… Pan Coating Press Coating The coating is done in a pan made of copper or stainless steel . The tablets to be coated is placed in a pan . After coating polishing is done polishing pan . This technique is used for sugar, film and enteric coating. The granules of coating material is prepared and layer of coating material is place above and below the preformed tablet . Drug core Process of tablet coating

Slide 31:

Types of coating… A. Sugar Coating Sugar coating is the process of coating tablet core with sucrose syrup and consequently evaporating the solvent of syrup with the help of hot air . Various stages of sugar coating: Sieving Sealing Sub coating Syrup coating Finishing Polishing

Slide 32:

Types of coating… B . Film Coating It is a single step process of coating tablet core with polymeric film The polymer solution is sprayed onto a rotating tablet bed followed by drying , which facilitates the removal of the solvent leaving behind the deposition of thin film of coating materials around each tablet. The thickness of such a coating is usually between 20 and 100 μm . Advantages: Protects the drug from atmospheric changes , such as light, air and moisture Coating is resistant to cracking and chipping The tablet becomes elegant

Slide 33:

Types of coating… C. Enteric Coating These are designed to bypass the stomach and get disintegrated in the intestine only. This type of special coating is done due to following reasons. Medicaments that produce severe irritation in stomach Medicaments that destroy in stomach Drugs absorption is better in intestine Delayed action is required

Slide 34:

Types of coating… D . Microencapsulation It is process or technique by which thin coating can be applied to small particles of solids thus forming microencapsules . Microencapsulation techniques are: Pan coating Fluidised bed coating Coacervation Elecctrostatic deposition Vacuum deposition Polymerisation Multiorific centrifugal process

7. Manufacturing defects in Tablets:

7. Manufacturing defects in Tablets a. Capping This is partial or complete removal of top or bottom of tablet . This occurs due to improper tablet compression . Reasons: Defective punches and dies, high speed of machine, excessive drying of granules. Defects can be removed by: Setting the punches, Regulate the speed of machine and dies properly, reduce the percentage of fines b. Picking and Sticking Removal/picking of tablet material by upper punch. Sticking of tablet material to die wall. Reasons: Use of small quantity lubricants , presence of excessive moisture in granules. Defects can be removed by: Proper quantity of lubricants in granules, dry granules. c,. Mottling Unequal distribution of color on surface of tablets . Reasons: Migration of dye from granules during process of drying Defects can be removed by: Drying the granules at lower temperature

Manufacturing defects in Tablets..:

Manufacturing defects in Tablets.. d. Weight variation Tablets of same batch do not have same weight. Reasons: Granules are not in uniform size, no proper mixing of lubricants, no uniformity in flow of granules. e. Hardness variation It is having the same causes as weight variation . The hardness depending upon the distance between lower and upper punches

8. Evaluation of Tablets:

8. Evaluation of Tablets 8.1. Shape of tablets 8.2. Appearance 8.3. Content of active ingredient in tablets 8.4. Uniformity of weight 8.5. Disintegration test 8.6. Dissolution test 8.7. Mechanical strength 8.8. Friability

Evaluation of Tablets…:

Evaluation of Tablets… 1. Shape of tablets: In pharmacopeias the shape of the tablet is defined as circular with flat or convex faces . 2. Appearance: The control of general appearance involves the measurement of size, shape, color, presence or absence of odor, taste etc. 3. Content of active ingredient in tablet: The amount of active ingredient in tablet is determined by doing the assay as stated in the monograph. Generally 20 tablets are indicated in monographs Limits are 90 (lower limit) and 110 (upper limit) percent. 4. Uniformity of weight: It is desirable that every individual tablet in a batch should be in uniform in weight . 20 tablets are selected randomly and the average weight is determined. The following percentage deviation in weight variation is allowed. S.No Average weight of tablet deviation Percentage 1. 80mg or less 10 2. 80 to 250 mg 7.5 3. 250 mg or more 5

Evaluation of Tablets…:

Evaluation of Tablets… 5. Disintegration test: Disintegration of tablet means to break the tablet into smaller pieces after swallowing. The time required to disintegrate the tablet is called “ Disintegration time ” The disintegration time varies from tablet to tablet depending upon the nature of drug and ingredients. In general pharmacopeias prescribed a limit of 15 min for most of the tablets. Assembly: Basket having six vertical cylindrical glass tubes . Two super imposed plastic plates holding vertical tubes above and blow. Woven wire gauze attached underside of lower plate. The entire assembly is placed in a 1000 ml beaker . The assembly should be lowered and raised b/w 28 to 32 times per minute in the liquid at 37 o C.

Evaluation of Tablets…:

Evaluation of Tablets… 6. Dissolution test: The test is done for measuring the amount of time required for a given percentage of drug substance in tablet to go into solution under specific condition in vitro . Apparatus: Cylindrical vessel (glass or transparent) having 1000ml capacity . An electric motor which is capable of rotating the shaft (attached to paddle or basket) of speed b/w 25 to 150 rpm. The vessel is clamped in water bath maintained at 37 o ±0.5 o C. Method: Place 900 ml of water in vessel and tablet in basket. Start the motor and adjust the rpm to 100. Withdraw the sample after certain periods of time. Filter and determine the amount of active ingredient present. Release of drug should be not less than 70% of the stated amount . No-retest is allowed .

Evaluation of Tablets…:

Evaluation of Tablets… 7. Mechanical Strength: No standards has been mentioned in pharmacopeias depends on manufactures requirements. a. Monsanto hardness tester: The tablet is placed b/w spindle and anvil From point zero, the pressure is applied till the tablets breaks . The reading is noted, indicates the pressure at which the tablets brakes. b. Pfizer tablet hardness tester: Principle based on plier . The tablet is placed b/w the jaws of the plier and pressure is applied by pressing the handles . The reading in dial is noted .

Evaluation of Tablets…:

Evaluation of Tablets… 8. Friability Test: Friability test is performed to evaluate the ability of the tablet to withstand wear and tear in packing , handling and t ranspiration . The apparatus used is friabilator . Assembly and Method It consists of plastic chamber , divided into two parts and revolves at a speed of 25 rpm. 20 tablets are placed in chamber and rotated for 4 min or 100 revolutions . After 100 revolutions the tablets are r e-weighed . Loss in weight indicates friability . The tablets are considered to be good quality if the loss in weight is less than 0.8%.

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