NTA Level 4 • Semester 1 • PST04104

Introduction to Pharmaceutical Dosage Forms

Pharmaceutical Dosage Forms • Source Session/Topic 1

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Session 1: Introduction to Pharmaceutical Dosage Forms

Total Session Time: 120 minutes

Prerequisites

• None

Learning Tasks

By the end of this session students are expected to be able to:

• Define Dosage Form

• Classify Pharmaceutical Dosage Forms According to their Physical Forms

and Routes of Administration

• Explain the Importance of Dosage Forms

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board, chalk and whiteboard markers

• Overhead projector

• Computer

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Definition of Dosage Forms (10 minutes)

| Activity: Brainstorming (5 minutes) |

|ASK students to brainstorm on the following question |

|What is dosage form? |

|ALLOW few students to respond |

|WRITE their responses on the flip chart or board |

|CLARIFY and SUMMARIZE their responses using the contents below. |

• Dosage forms:

o These are the means by which drug molecules are delivered to the sites

of action in the body

o They are the drug delivery systems

o Example of pharmaceutical dosage forms are tablets, capsules, syrups,

suspensions, injections, creams and ointments

o Selection of right dosage forms depends on the situation of a patient

(emergency or unconscious) and the location of the disorder

STEP 3: Classification of Dosage Forms (75 minutes)

|Activity: Small Group Discussion ( 30 minutes) |

| |

|DIVIDE students into small manageable groups |

| |

|ASK students to discuss on the following question |

|What are the classes of Pharmaceutical dosage forms? |

| |

|ALLOW students to discuss for 15 minutes |

| |

|ALLOW few groups to present and the rest to add points not mentioned |

| |

|CLARIFY and SUMMARIZE by using the contents below |

• Dosage forms are classified according to Physical forms and Route of

administration

• Classification according to physical forms

o Solid dosage forms

▪ The solid dosage forms are mainly of two types, tablets and

capsules. Others are powders, pills and cachets

▪ Tablet is a compressed solid dosage form (of uniform volume of

particles) containing medicaments with or without excipients

▪ Capsules are solid preparations with hard or soft containers

“shells”, (commonly but not exclusively of gelatine) of various shapes

and capacities, usually containing a single dose of active

ingredient(s)

▪ he solid dosage forms are advantageous as they ensure the means

for accurate dosing, portable (lighter) and easy handling , cheap for

large scale production, easy to control quality and masking unpleasant

tastes

o Semisolid dosage forms

▪ Semisolid preparations comprise a number of products, which when

applied to the skin or accessible mucous membranes tend to alleviate

or treat a pathological condition or offer protection against a

harmful environment

▪ They are intended for local drug delivery on the skin, cornea,

rectal tissue, nasal mucosa, vagina and others

▪ Most of them are non-irritating

▪ Examples are ointments, creams, gels, pastes and poultices

o Liquid dosage forms

▪ Liquid dosage forms are homogeneous or heterogeneous preparations

containing one or more active ingredients in a suitable vehicle

▪ The liquid dosage forms are advantageous as they are more readily

available for absorption, easily swallowed than tablets or capsules

and therefore suitable for children and elderly patients

▪ The gastric irritation caused by certain drugs when they are

administered as a solid dosage form may be reduced or avoided when

liquid dosage forms are used

▪ The disadvantages of liquid dosage forms include; less stability in

liquid formulation, susceptibility to microbial contamination,

difficultness in masking unpleasant taste and inconvenience to store

and transport due to bulkiness

▪ Also administration of the correct dose is less precise since in

involves the use of 5ml spoon, an oral syringe or volumetric dropper

and the dispersion systems have to be shaken before use to allow

accurate dosage

▪ Examples of liquid dosage forms are solutions, suspensions, spirits,

tinctures, mixtures and others.

o Gaseous dosage forms

▪ The small drug particles are usually compressed with air

▪ These forms include aerosols and inhalers

• Classification according to Route of Administration

o Oral dosage forms

▪ Are usually intended for systemic effects resulting from drug

absorption through the various mucosa of the gastrointestinal tract

▪ It is the simplest, most convenient and safest means of drug

administration

▪ The onset of action depends on the rate of absorption

▪ The disadvantages include relatively slow onset of action,

possibilities of irregular absorption and destruction of certain drugs

by enzymes or secretions of the gastrointestinal tract

▪ The most popular oral dosage forms are tablets, capsules,

suspensions, solutions and emulsions

o Parenteral dosage forms

▪ These are medicines which injected via a hollow needle in to the

body at various sites.

▪ The main parenteral routes are subcutaneous (S.C), intramuscular

(I.M) and intravenous (I.V) and the less frequently used intrathecal

▪ The parenteral route is preferred when rapid absorption is

essential, as in emergency situations or when patients are unconscious

or unable to tolerate oral dosage forms

▪ Absorption after parenteral drug delivery is rapid

▪ Injectable preparations are usually sterile suspensions or solutions

of drugs in water or other physiologically suitable and acceptable

vehicles

o Rectal dosage forms

▪ They are usually administered for local rather than systemic effects

▪ The formulations may be in solution, suppository or emulsion form

▪ Suppositories are solid forms intended for introduction to cavities

(usually rectal, but also vaginal and urethral) where they melt and

release the drug

▪ This route is usually used when there is a suspicion of inactivation

of oral dosage forms by intestinal fluids or when the patient is

unconscious or vomiting

▪ This route does not allow drugs to pass through the liver hence

prevent them from being metabolized by liver enzymes

▪ The disadvantages of this route include; a slower absorption than

other routes, irregularity or uncompleted absorption and irritation to

the mucosa at the site of application

o Vaginal dosage forms

▪ The preparations in this group are employed principally to combat

infections in the female genitourinary area, to restore the vaginal

mucosa into normal state and contraception

▪ Vaginal tablets (inserts) are mostly used than the vaginal

suppositories because are easy to manufacture, handle in use and more

stable

o Inhaled dosage forms

▪ These drugs are applied through respiratory route. Lungs provide an

excellent surface for absorption when the drug is in gaseous or

aerosol mist form

▪ The aerosols droplet particle size determines the extent to which

the drug penetrates the alveoli region

▪ The smaller the particle size the larger the amount of drug reach

the alveolar sacs

▪ This route introduces drug throughout the respiratory tract (site of

Action)

▪ This route has been found useful in the treatment of asthmatic

condition

▪ The main disadvantages of the respiratory route is a poor regulation

of the dosage and the drug may spread to other parts more than

respiratory tract

o Topical dosage forms

▪ The drugs are applied topically, usually to the skin for local

action

▪ This route can also be used for systemic drug delivery

▪ Percutaneous absorption is generally poor and erratic

▪ Drug absorption is via the sweat glands, hair follicles, sebaceous

glands and the stratum corneum

▪ Example of drugs applied to the skin for local effect includes

antiseptics, antifungal, anti-inflammatory agents and skin emollients

(for protective effects)

▪ Examples of topical pharmaceutical formulations are ointments,

creams and pastes

▪ The side effects of topical dosage forms are few

▪ The main disadvantage is that the drug may enter the body through

abrasions and cause systemic effects

o Ophthalmic and otic dosage forms

▪ The dosage forms and delivery systems applied to the eye include

solutions, suspensions, gels and ointments

▪ Pharmaceutical preparations are applied topically to the eye to

treat surface or intraocular conditions including viral infections,

bacterial infections, fungal infections, elevated intraocular

pressure or glaucoma and dry eye due to an inadequate production of

fluids bathing the eye

▪ They may also be applied topically to the ear to treat ear

conditions

STEP 4: Importance of Dosage Forms (20 minutes)

|Activity: Buzzing (5 minutes) |

| |

|ASK students to pair up and buzz on the following question for 2 |

|minutes |

| |

|What is the importance of dosage forms? |

| |

|ALLOW few pairs to respond and let other pairs to add on points not |

|mentioned |

| |

|WRITE their response on the flip chart/board |

| |

|CLARIFY and SUMMARIZE by using the content below |

• The dosage forms of most drugs gives the public an expectation that,

they take safe and appropriate dose of a drug from bulk materials

• Besides providing the mechanism for the safe and convenient delivery

of accurate dosage, dosage forms are needed for the following reasons:

o Protection of a drug substance from the destructive influences of:

▪ Atmospheric oxygen or humidity. (e.g. coated tablets, sealed

ampoules)

▪ Gastric acid after oral administration (e.g. gastric-coated tablets)

• Mask the bitter, salty and offensive taste and odour of a drug

substance (e.g. capsules, coated tablets, flavoured syrups)

• Provide right suspending materials depending on the preparation (e.g.

suspensions, syrup)

• Provide rate controlled drug actions (e.g. controlled release tablets)

• Provide optimal drug action according to the route of administration

(e.g. ointments for topical sites, suppositories for body’s orifices,

injections for direct bloodstream or body tissue delivery and

inhalations for respiratory system delivery)

STEP 5: Key Points (5 minutes)

• Dosage forms are the means by which drug molecules are delivered to the

sites of action in the body

• Dosage forms are classified according to Physical forms and Route of

administration

• The dosage forms of most drugs gives the public an expectation that

they take safe and appropriate dose of a drug from bulk materials

STEP 6: Evaluation (5 minutes)

• What is dosage form?

• What are the different classes of pharmaceutical dosage forms?

• What is the importance of pharmaceutical dosage forms?

References

Aulton, M.E., Taylor, M.K. (2001). Pharmaceutics: The Science of dosage

form design

(2nd ed.). USA: Churchill Livingstone

Cooper, J.W., Gunns, C., & Carter, S.J. (2008). Dispensing for

Pharmaceutical Students

(12th end). Delhi, India: CBS Publishers and Distributors.

Rawlins, E.A. (2001).Bentley’s Textbook of Pharmaceutics (8th ed.). London,

UK:

Bailliere Tindall.

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