Tablets for GPAT...-2

Tablets for GPAT...-2

TABLETS:

Minimum area required for tablet preparation: 30sq.m

Minimum area required for hard gelatin capsules: 20 sq.m

Minimum area required for parenteral preparations: 60sq.m

Minimum area required for wholesale drug store: 200 sq.m

Minimum area required for retail drug store: 150 sq.m

Drugs which are not used in tablet preparation 

      I.            Drugs which have low density. 

     II.            Drugs which have poor wetting property.

Methods for preparation of tablets:

        I.            Wet granulation   

       II.            Dry granulation   

      III.            Direct granulation

       In wet screening 12 – 20 microns mesh size is used.

LACTOSE: not used as diluent in spironolactone preparation because it increases bioavailability.

MANNITOL: used as diluent and binding agent in preparation of chewable tablet.

Enteric coating causes 1 -3% increase in weight of tablet.

Film coating causes 2 -6% increase in weight of tablet.

Sugar coating causes 50 % increase in weight of tablet.

Mixing in tablet preparation by: 

      I.            Mixer.   

     II.            Double cone mixer: speed 30 – 100 rpm.   

    III.            Planetary motion mixer: used to mix binding agent to drug.

Binding agents:   

      I.            Water : for hydrazable materials 

     II.            Alcohol – methanol

    III.            Acacia mucilage : 10 – 20% is used 

    IV.            Tragacanth mucilage : 10 – 20 % is used 

      V.            Starch mucilage: 5 – 10% is used. It improves intragranular adhesion. 

     VI.            Simple syrup : 66.6% w/w

                                          85% w/v

Every 2 grams of sucrose preserves 1gm of water from microbial attack.        

Artificial sweeteners:   

    I.            Saccharin sodium: 200 – 300 times sweeter than sucrose.   

    II.            Cyclamate: 30 times sweeter than sucrose. causes cancer

    III.           Aspartate: 200 times sweeter than sucrose. 

    IV.            Glycerol: it is glycogenic in nature, hence not used for diabetic patients.   

     V.            Xylitol: used in diabetic patients.

3% PVP in isopropyl alcohol used as binding agent in non – aqueous granulation.

Types of tablets:   '

    I.             Compressed tablets 

    II.            Multiple compressed tablets. 

  III.            Repeat action tablets: core tablet is coated with enteric polymer/ shellac. the second                                                           Dose of drug is added in sugar coating either in solution or

                                                        syrup   Form or as dusting powder. 

  IV.            Delayed and enteric coated tablets :

 All enteric coated tablets are delayed action tablets, not all delayed action tablets are enteric.   

  V.            Film coated tablet 

  VI.            Tablets used in oral cavity :

                     Buccal and sublingual tablet.

                     Lozenges.

                     Dental cones.

   VII.            Other routes:

                                           implantation tablets,

                                           vaginal tablets.

1. Tablets used to prepare solution

:Effervescent tablets

Dispensing tablet

Hypodermic tablets

Tablet triturates.

Different diluents used in tablets:

         I.            Starch :

For example: sta – Rx 1500: contain 10 % moisture.

Two hydrolyzed starches EMDEX and CELUTAB basically 90 – 92 % dextrose and 3 – 5% maltose. These materials are used in place of mannitol in chewable tablets because of their sweetness and smooth feeling in mouth.

       II.            Dextrose : trade name CERELOSE    III.            Sucrose :

                           For example: sugartab: 90 – 93% sucrose + 7 – 10% invert sugar.

                                                    Dipac       : 97% sucrose + 3% modified dextrins

                                                    Nutab      : 95% sucrose + 4% invert sugar

    IV.                            Microcrystalline cellulose : trade name : AVICEL

DISINTEGRANTS:

Starch 5 -20 % concentration. : PRIMOGEL AND EXPLOTAB.

Internally cross – linked polymer of sodium carboxy methyl cellulose: AC – Di – SOL

GLIDANTS:

Talc: 5% concentration

Corn starch: 5 – 10 % concentration.

Colloidal silica: cab – o – sil, syloid, aerosil: 0.25 – 3% concentration.

FLAVOURS:

The maximum amount of oil that can be added to granulation without influencing its tableting characteristics: 0.5 – 0.75%

EVALUATION OF TABLETS:

1.         i.            Flow property :

                             Angle of repose: tan ø = h/r

                             Angle of repose:               flow property

                                     < 25                             excellent flow property

                                        25 -30                        good flow property

                                        30 -40                         fair to possible.

                                  More than 40                    very poor.

Also see the Carrs index table and hessners ratio .

       ii.            Hardness test : the hardness must not be less than 4Kg/cm2.

     iii.            Friability :       the friability limit must not be more than 2%.

                          The working of Roche frailibilator is very imp and its dimensions.

      iv.            Disintegration : very imp

                   Uncoated tablets : should disintegrate within 15 min. by using water as medium.

                   Film coated tablets: disintegrate within 30 min by using water, adding disc to       

                                                     Each tube. (37 ± 2°C)

                   Other coated tablets: tablets should disintegrate within 60 min, by using water   

                                                      As medium.

                   Enteric coated tablets: 120 minutes in acidic medium.

                                                         60 minutes in mixed phosphate buffer medium.

                   Dispensable and soluble tablets : within 3 min. water as medium. Temp 24 -26°C.

                   Effervescent tablets : within 5 min as water. ( 20 - 30°C)

For uniformity of dispersion 710 µ mesh is used.

The dimensions and details of instruments used in evaluation of tablets and capsules are very imp. For GPAT  read them.

According to USP weight variation test is run by weighing 20 tablets.

Content uniformity test is performed by taking 30 tablets randomly.

Interaction of amine drugs with commonly used diluent lactose, in presence of metal stearate lubricant the resultant tablets gradually decolorized with time: this is called MAILLARD REACTION.

Anhydrous lactose does not show maillard reaction.

Crown thickness is measured by : micrometer and sliding caliper scale.

Processing problems are very imp read them from lachman.