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Al-Achi, A. J.

Campbell University 
CU FIND 
Pharmaceutical Sciences Pharmacy & Health Sciences, College of 
2019 
Tablets: a brief overview 
A. J. Al-Achi 
Follow this and additional works at: https://cufind.campbell.edu/pharmacy 
 Part of the Pharmacy and Pharmaceutical Sciences Commons 
Journal of Pharmacy Practice and Pharmaceutical Sciences [ISSN: 2652-2536]                                                            Submit Manuscript 
.01.                                                            
                                                                                                                                                                                                         
OCIMUM
Mini Review
Tablets: A Brief Overview
Antoine Al-Achi*
College of Pharmacy & Health Sciences, Campbell 
University, North Carolina, USA
Received: 15 March, 2019
Accepted: 10 May, 2019
Version of Record Online: 03 June, 2019
Citation
Al-Achi A (2019) Tablets: A Brief Overview. J 
Pharm Pract Pharm Sci 2019(1): 50-53.
Correspondence should be addressed to
Antoine Al-Achi, USA
E-mail: alachi@campbell.edu
Copyright
Copyright © 2019 Antoine Al-Achi. This is an 
open access article distributed under the Creative 
Commons Attribution License which permits 
unrestricted use, distribution, and reproduction 
in any medium, provided the original author and 
work is properly cited.
Abstract
Solid dosage forms, such as tablets, are widespread in practice. This is due to the 
ease of administration and capability of mass production by the pharmaceutical 
industry. Tablet formulation consists of the active ingredient along with fillers that 
serve various functions in the product. Tablets are prepared on machines known 
as presses. Material to be compacted is ready by either dry or wet methods. The 
United States Pharmacopeia lists tests to be performed on the finished products. 
A description of tablets, their characteristics, preparation, and quality control 
tests applied to them is the subject of this brief review.
Introduction
As a solid dosage form, tablets are prepared from dry powders containing 
pharmacologically active and inert ingredients. Most drug products available 
on the market are found in the form of tablets. Tablets are found on the 
market in different shapes, weight, colors, disintegration time, dissolution 
time, and for various routes of administration [1]. The oral tablets are 
usually easily swallowed and provide either an immediate drug action or a 
sustaining effect. In addition to the Active Pharmaceutical Ingredient (API), 
a tablet formulation may contain one or more of the following essential 
parts: Diluents, binders, lubricants, glidants, anti-adherents, disintegrating 
substances, coloring agents, flavoring and sweetening agents, and absorbents 
[2]. The instrument that forms powders into tablets is known as a tablet press. 
Tablets may be prepared either using dry methods or by wet granulation 
[3]. In this paper, the basic ingredients that are commonly found in tablets 
are briefly reviewed along with quality control tests performed on the 
finished product. The objective of this paper is to present the reader who 
is not familiar with tablet formulations the basic information available on 
this dosage form.
Ingredients
Table 1 summarizes and provides examples of ingredients that are commonly 
found in tablet formulations [4,5].
The bulk of the tablet formulation is made of diluents, also known as 
bulking agents. Microcrystalline cellulose (Avicel®) is commonly found in 
formulations as well as lactose. Starch from corn, rice, or wheat is also a 
possible bulking material for tablets. A couple of sugars, sorbitol, and mannitol 
may be found in tablets formulation serving as diluents. Avicel® is useful 
in tablets that are formulated by direct compression because it possesses 
binding and disintegrating properties. Other directly compressible vehicles 
Journal of Pharmacy Practice and Pharmaceutical Sciences
ISSN: 2652-2536
10.33513/PPPS/1901-10
Al-Achi A. J Pharm Pract Pharm Sci 2019(1): 50-53.
 Submit Manuscript                                             Journal of Pharmacy Practice and Pharmaceutical Sciences [ISSN: 2652-2536]
.02.
are calcium phosphate, spray-dried lactose, and anhydrous 
lactose. There also exist pre-blended vehicles where the API 
is added directly to the dry powder vehicle and compressed 
as is. Sta-Rx 1500 is an example of such as a vehicle with self-
binding and disintegrating properties. An interesting diluent 
for tablets is Emdex® which is hydrolyzed starch. Emdex® may 
be used whenever greater strength in tablets is desirable [4].
Tablet Ingredients Examples
Diluent Calcium Phosphate; Carboxymethylcellulose Calcium; Cellulose; Dextrin; Lactose; Microcrystalline Cellulose; Pregelatinized Starch; Sorbitol; Starch
Binders
Acacia; Alginic Acid; Carboxymethylcellulose; Cellulose; Dextrin; Gelatin; Liquid Glucose; 
Magnesium Aluminum Silicate; Maltodextrin; Methylcellulose; Povidone; Sodium Alginate; 
Starch; Zein
Lubricants Calcium Stearate; Glyceryl Palmitostearate; Magnesium Oxide; Poloxamer; Polyvinyl Alcohol; Sodium Benzoate; Sodium Lauryl Sulfate; Sodium Stearyl Sulfate; Stearic Acid; Talc; Zinc Stearate
Glidants Magnesium Trisilicate; Cellulose; Starch; Talc; Tribasic Calcium Phosphate
Anti-adherents Corn Starch; Metallic Stearate; Talc
Disintegrants Alginic Acid; Carboxymethylcellulose; Cellulose; Colloidal Silicon Dioxide; Croscarmellose Sodium; Crospovidone; Potassium Polacrilin; Povidone
Coloring Agents FD&C or D&C Dyes or Lake Pigments
Flavoring Agents Ethyl Maltol; Ethyl Vanillin; Menthol; Vanillin
Absorbents Kaolin; Magnesium Aluminum Silicate; Tricalcium Phosphate
Table 1: Commonly added ingredients in tablet formulations.
Although the diluent has its cohesiveness and perhaps can 
hold the powder particles together to form a tablet, binders 
are often used to ensure that tablets maintain their shape 
throughout their life cycle (i.e., from manufacturing to the use 
by patients). Binders act as a glue adding to the cohesiveness 
existing between solid particles. During formulations, binders 
are commonly added moist rather than in their dry form. The 
reason being is that the efficiency of binding the solid particles 
is enhanced in the presence of water. Exceptions to this do 
exist. For example, tragacanth gum is a better binder when 
added in its dry form than when it is moist. Acacia dispersion 
in water (10% w/w) is a suitable binder when mannitol is used 
as a diluent. A 10% solution of gelatin in water also serves as 
a binder, and so do syrups (50% to 65% w/w of sucrose in 
water). Although starch is considered a diluent when found 
in relatively large amount in the tablet formulation, it can 
also work as a binder after hydrating it with water (2% w/w). 
Colloidal guar gum dispersions in water may be used for 
binding solid particles as well [4-6].
Lubricants play an important role in tablet formulations as they 
reduce the friction between the tablet formulation and the tablet 
press walls, preventing ware and tare. Examples of lubricants 
are magnesium stearate and silicon dioxide. Lubricants are 
found in concentrations less than 1% w/w. Glidants on the 
other hand help improve the flow characteristics of the material 
being compressed. They achieve this by reducing inter particle 
friction. Corn starch in concentrations of 5-10% w/w can 
act as a glidant. Formulators add anti-adherents to the tablet 
formulations to prevent the material from sticking to the walls 
of the tablet press. Talcum powder is one of such agents and is 
used in concentrations of 5% w/w. Lubricants, glidants, and 
anti-adherents are added and mixed with the granulation just 
before compression [1-6].
Disintegrants are added to the formulation to allow the tablet 
to break apart upon contact with water. These agents tend to 
swell when they encounter water and thus break apart the 
tablet and cause it to disintegrate. Cellulosic materials and 
natural gums, as well as starch, may be used to function in 
this capacity. The typical concentration of disintegrants in 
formulations is between 0.5% to 5% [2,4,6].
The inclusion of absorbents in a tablet formulation is necessary 
if the product contains a substance with a high affinity to water. 
Hygroscopic materials, if present, render the blend wet and 
difficult to handle during manufacture. Silicon dioxide can 
absorb excess moisture and remain a dry powder. Examples of 
other absorbents are kaolin, bentonite, dry starch, tricalcium 
phosphate, Veegum® (colloidal magnesium aluminum silicate), 
magnesium oxide, and magnesium carbonate [4].
Coloring agents may be employed in tablet formulations 
to render the tablet aesthetically appealing and to perhaps 
distinguish one product from another by the color of the 
tablet. However, coloring agents may also serve to establish 
visual homogeneity of the blend once the color is uniformly 
distributed in the mixture. During wet granulation, the dye 
is dissolved or dispersed in the binder solution and added 
to the mix along with the binder. FD&C or D&C dyes or 
Citation: Al-Achi A (2019) Tablets: A Brief Overview. J Pharm Pract Pharm Sci 2019(1): 50-53. DOI:10.33513/PPPS/1901-10
Lake pigments may be used in the tablet formulation. Lake 
pigments, unlike dyes, are insoluble in water and they color 
by dispersion. Lake pigments are more suited to color solid 
dosage forms such as tablets [1,4].
Flavoring oils are needed for chewable tablets. The oil is 
generally added in a dry form such as spray-dried beadlets. 
An excess amount of the flavor oil can interfere with the flow 
ability of the granulation, and thus its concentration in the 
blend is kept at 0.5% or less [4,6].
Ingredients that may be included in a tablet formulation are 
often chosen by experimental and scientific knowledge in the 
field of manufacturing solid dosage forms as well by applying 
mathematical modeling such as the Design of Experiment 
(DoE). The utilization of DoE in finding the best composition 
of a tablet formulation may be achieved by choosing a 
proper design, defining a study domain, and by conducting 
experimentation. Among the useful designs in this respect are 
mixtures design and custom design (also known as D-optimal 
design). Whereas the latter allows more flexibility in choosing 
the appropriate amount of ingredients to be tested, the former 
is applied with the constraint that the sum of ingredients for a 
given formulation must be 100%. Statistical programs such as 
JMP Statistical Discovery Software (SAS Institute, Cary, NC) 
may be used to run the DoE planning and analysis. When 
applying the DoE on tablet formulation, the operator has to 
define at least one measurable outcome, define the ranges of the 
quantity of each ingredient to be tested within the formulation, 
and finally determine the number of runs (experiments) that 
should be performed. Each experiment in the DoE table then 
is executed by the operator and the value of the outcome 
is recorded. Once all the data are collected, the results are 
analyzed and the best composition for the tablet formulation is 
then obtained. As a proof of concept, this formulation is then 
prepared multiple times and subjected to further testing in order 
to define its suitability for manufacturing. The application of 
DoE in formulation is currently considered to be the state of 
art in preparing dosage forms.
Tablet Preparation
As mentioned above, tablets are made on machines known 
as presses. These can be single-punch or multi-stationary 
presses. The main components of a press are the hopper, 
guiding scrapers, dies, punches, and cams. The material to 
be tableted is placed in the hopper and with the help of the 
feeders is distributed into the die cavity. The upper punch 
descends with force guided by cams to compress the material 
into a tablet. The formed tablet is then released from the die 
cavity with the movement of the lower punch. The position 
of the lower punch inside the die determines the size of the 
die cavity. Thus, dies shape and control the size of the tablets. 
Punches also influence the shape of the tablets as well. Some 
tablets are shaped like capsules for easy swallowing the unit 
[4]. These are known as caplets.
Two methods of making tablets are recognized. These are the 
dry methods and wet methods. The dry methods are of two 
types, direct compression, and granulation by compression. The 
first method relies on the presence of a directly compressible 
vehicle. The API is added to the vehicle and compressed. 
Granulation by compression includes formation of a large, 
poorly formed tablets (known as slugs), followed by gridding 
the slugs into granules. The resulting granules are made into 
slugs and then one more time made into granules. These 
final granules are then compressed into tablets. Due to twice 
formation of granules and slugs, the cohesive forces in the 
mixture is strong enough, and thus binders are not needed 
in the formulation. Moreover, since no water is used during 
the preparation of slugs or granules, there is also no need for 
drying steps [1-3].
In wet granulation methods, the API is mixed homogeneously 
with other fillers that include half the quantity of disintegrants 
and then wetted with an aqueous dispersion of the binder 
containing the dye. Following proper mixing, the wet mass 
is then forced through sieve openings to form granules. The 
resulting granules are dried and passed again through sieve 
openings smaller than the ones used before. Lubricants, glidants, 
anti-adherents, and half the quantity of disintegrants are added 
to the granules and mixed. The resulting dry granulation 
mixture is finally compressed into tablets. As a rule, small 
tablets require small granules and large tablets need large 
granules [1-3].
Quality Control Tests
The United States Pharmacopeia (USP) lists several tests to be 
performed on the finished tablets to assure their suitability to 
be used in therapy [1,2]. These tests are also essential to ensure 
that various batches of the same products produce consistent 
results on these tests. For more details on these tests, the reader 
is referred to the USP 41/NF 36.
Tablet breaking force tests the hardness of the tablet. Too 
much binder in the formulation produces hard tablets. If the 
tablet is soft, it can be damaged easily by handling, packaging, 
or shipping. On the other hand, too hard tablets cannot 
disintegrate easily, and the bioavailability of the API from the 
tablets is significantly affected.
Friability test examines the amount of material lost from tablets 
Citation: Al-Achi A (2019) Tablets: A Brief Overview. J Pharm Pract Pharm Sci 2019(1): 50-53. DOI:10.33513/PPPS/1901-10
Journal of Pharmacy Practice and Pharmaceutical Sciences [ISSN: 2652-2536]                                                            Submit Manuscript 
.03.                                                            
                                                                                                                                                                                                         
after subjecting them to fall from a 6-inch hight while they are 
rotated 100 times (25 rotations/minute for 4 minutes). Tablets 
(20) are weighed before the test and immediately following 
the rotation. For the batch of tablets to pass this test, the loss 
in their weight should be less than 1%. In the case of capping 
(loss of top or bottom of the tablet) during the friability test, 
the tablets fail this test regardless of the weight loss.
Disintegration test is required to assure that the tablets can 
break apart when they contact aqueous fluids. The test utilizes 
a basket made of a mesh screen at its bottom and six columns 
where the tablets are placed, one tablet per column. The basket 
is then immersed in 900 mL of water (37°C) and moved up 
and down with the help of a motor that controls a handler 
where the basket is attached to it. For most immediate release 
tablets, their disintegration time is within a few minutes.
Among the important tests to be performed on the finished 
tablets is the dissolution test. The test utilizes six round-bottom 
flasks that are placed in a water bath for temperature control 
(37°C). One tablet is placed in each flask containing the test 
medium (usually water, 900 mL). It is expected that at a 
minimum 70-75% of the API is dissolved in the test medium 
within 30-45 minutes. In practice, for most immediate release 
tablets, a minimum of 90% of API is dissolved within 30 
minutes.
Weight variation test requires the selection of 10 tablets from 
the tablets batch and pulverizing them together in a mortar. 
A weight equivalent of a single tablet is then taken from the 
powder mixture and analyzed for its content of API. This 
amount is then compared with the labeled amount of the 
API in the product.
Content uniformity test is like the weight variation test. 
References
1. Allen LV (2016) The Art, Science, and Technology of 
Pharmaceutical Compounding. 5thedn, American Pharmacists 
Association, Washington, DC, USA.
2. Al-Achi A, Gupta MR, Stagner WC (2013) Integrated 
Pharmaceutics: Applied Preformulation, Product Design, 
and Regulatory Science. John Wiley & Sons, Hoboken, New 
Jersey, USA.
3. Allen LV, Ansel HC (2013) Ansel’s Pharmaceutical Dosage 
Forms and Drug Delivery Systems. Wolters Kluwer Health, 
Alphen aan den Rijn, Netherlands.
4. Lachman L, Lieberman HA, Kanig JL (1976) The Theory 
and Practice of Industrial Pharmacy. 2ndedn, Lea & Febiger, 
Philadelphia, Pennsylvania, USA.
5. Kibbe AH (2000) Handbook of Pharmaceutical Excipients. 
3rdedn, American Pharmaceutical Association, Washington, 
DC, USA.
6. Parrott EL (1970) Pharmaceutical Technology: Fundamental 
Pharmaceutics. Burgess Publishing Company, Minneapolis, 
Minnesota, USA.
However, the API content in 10 different random tablets is 
determined individually.
Conclusion
As a solid dosage form, tablets are popular among patients and 
practitioners alike as they provide a means of self-administration. 
The formulation of a tablet contains, in addition to the API, 
various substances to assure proper delivery of the API to the 
patient. Quality control tests on the finished products are 
required and follow USP standards.
Citation: Al-Achi A (2019) Tablets: A Brief Overview. J Pharm Pract Pharm Sci 2019(1): 50-53. DOI:10.33513/PPPS/1901-10
 Submit Manuscript                                             Journal of Pharmacy Practice and Pharmaceutical Sciences [ISSN: 2652-2536]
.04.


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