Dosage Forms And Routes Of Administration

DOSAGE FORMS AND ROUTES OF ADMINISTRATION

Introduction to routes of administration: Drug substances are rarely administered in their natural or pure state. They are usually administered in combination with one or more nonrnedicinal agents that serve different and specialized pharmaceutical functions. The selective use of these nonrnedicinal

agents,

called

as

pharmaceutical

ingredients

(components /parts), helps, adjuncts (supports), or necessities different pharmaceutical preparations. The pharmaceutical ingredients are used to solubilize (dissolve), suspend, thicken (harden), dilute, emulsify, stabilize, and preserve the pharmaceutical preparations. Some pharmaceutical ingredients are also used as coloring agents and flavoring agents (flavoring agents are used to hide or mask the bitter test of drugs). Every intention to use pharmaceutical ingredients is to improve the quality (efficacy) and also to make the pharmaceutical preparations attractive for the consumer (user). The pharmaceutical preparations with particular characteristics presented (given) to the patients are called as dosage forms.

[Pharmaceutics: The general area of study related with the physical, chemical and biological factors influencing the formulation, manufacturing, stability and effectiveness of pharmaceutical dosage forms is called as pharmaceutics]. Importance or need for dosage form: Most of the drugs are highly biologically active and hence exact dosage (quantity) of every drug is to be administered. Further, age of patients, condition of patients, general liking (choice) of patients, site of application etc. are different factors that made the pharmacists to design (plan to prepare) dosage forms. The importance or need to prepare dosage forms may be summarized as follows1) To provide safe and convenient administration of drug substance in accurate dosage (quantity). 2) For protection of drug substances from destructive influence of atmospheric oxygen and moisture (e.g. coated tablets, sealed ampules etc.). 3) For protection of drug substances from destructive influence of

gastric acid after oral administration (e.g. enteric coated tablets). 4) To conceal (hide or mask) the bitter, salty, or obnoxious (hateful) taste or (smell) of a drug substance (e.g. capsules, coated tablets, flavored syrups etc.). 5) To provide liquid preparations of substances that are insoluble or unstable in the desired vehicle (medium), (e.g. suspensions). 6) To provide liquid dosage forms of substances that are soluble in the desired vehicle (medium), (e.g. solutions). 7) To provide extended drug action through controlled release mechanism

(e.g.

various

controlled

release

tablets,

capsules

andsuspensions). 8) To provide optimal drug action from topical administration sites (e.g. ointments, creams, ophthalmic (related to eye), ear and nasal preparations). 9) To provide for the insertion of a drug substance into one of the body's

orifices

(opening/

aperture/

outlet) (e.g.

rectal

or

vaginal suppositories). 10)

To provide for the placement of drugs within body tissue

(e.g.injections). 11)

To provide optimal drug action through inhalation therapy

[e.g.inhalants

(vicks)

and

inhalation

aerosols

(used

asthmatic patients). Routes

of

administration,

administration: (i.e. The

route

There

are

different

routes

of

by which the drug is placed

(regulated/given or taken). The

list

term

(name/designation) and the site of routes of

administration of drugs are given as :-

by

S. No.

Term

Site

1)

Oral

Mouth

2)

Per-oral

Gastro intestinal tract (via mouth)

3) 4)

Sublingual Parenteral

4) a) Intramuscular 4) b) Intravenous

Under the tongue Other than gastro intestinal tract (by injection) Muscle Vein

4) c) Intraarterial

Artery

4) d) Intracardiac

Heart

4) e) Intra synovial

Joint-fluid area

4) f)

Joints

Intraatrticular

4) g) Intracutaneous or Skin intradermal 4) h) Subcutaneous Beneath the skin 5)

Skin surface

6)

Epicutaneous (topical) Conjunctival

7) 8)

Intraocular Intranasal

Eye Nose

9)

Aural

Ear

10)

Intrarespiratory

Lung

11)

Rectal

Rectum

12)

Vaginal

Vagina

13)

Urethra!

Urethra

Conjunctiva

Variety of Dosage Forms: There are different forms into which a drug may be placed (regulated/given or taken) for convenient and effective treatment of disease. Drugs can be prepared for administration by very conceivable (convincing) route and the suitable preparation is formulated to insure maximum therapeutic (curative) response. These may be tablets, capsules, solutions, syrups, elixirs, suspensions, gels, powders, troches or lozenge, ointments, creams, pastes, aerosol, lotions, sprays, inhalants, emulsions and suppositories. The preferred dosage forms in different routes of administration is listed as:-

S. No.

Term

1)

Oral

2)

Sublingual

3)

Parenteral

4)

Epicutaneous (topical)

5) 6)

Conjunctival

Tablets Capsules Solutions Syrups Elixers Suspensions Gels Powders Tablets Troches or Lozenge Solutions and Suspensions Solutions Suspensions Gels Powders Ointments Creams Pastes Aerosol Lotions Sprays Ointments and Solutions

Intraocular/Intraaural Solutions and Suspensions

7)

Intranasal

8)

Intrarespiratory

9)

Rectal Vaginal

10)

11)

Site

Urethra!

Solutions Ointments Aerosol Sprays Inhalents Aerosol Solutions, Ointments and Suppositories Tablets Solutions Ointments Emulsions and Suppositories Solutions and Suppositories

Advantages and Disadvantages of oral rout of administration: Drugs are usually taken by oral route of administration. The Advantages and disadvantage of oral route of administration are discussed below Advantages of oral route of administration: 1) It is most natural route of administration. 2) It is most easy route for administration of drug for patients. 3) It is safest route of administration. 4) It is most convenient for patients. 5) This route can take large variety of dosage forms. 6) Nursing for administration is not required. 7) An allergic reaction of the drug (toxicity) is delayed and hence safe. 8) It is economical to the patients. Disadvantages of oral route of administration: 1) The onset of action of drug is late and hence recovery is not fast. Therefore oral route of administration not preferred in emergency. 2) As it is absorbed from gastrointestinal tract the quantity of doses of drug required is more. 3) It

is

difficult

route

of

administration

of

drug

for

non-

cooperative patients like babies and children. 4) It is also difficult route of administration of drug for unconscious patients. 5) The absorption of drug from gastrointestinal tract is not assured by patients suffering from gastrointestinal disorder. 6) Oral route of administration may cause gastrointestinal disorders like acidity, loss of appetite, etc. 7) The

uncertainty of maintenance

of the

prescribed

dosage

of

drug is possible in oral route of administration. 8) Drug enzyme

may

be

destroyed

or

inactivated

by

the

in gastrointestinal tract.

Advantages and Disadvantages of parenteral rout of administration: Taken by parenteral route of administration, The Advantages and Disadvantages

of parenteral rout of administration are discussed belowAdvantages of parenteral route of administration: 1) The onset of action of drug is fast and hence recovery is fast. Therefore

parenteral

route

of

administration

preferred

in

emergency. 2) As it is administered directly on the site or nearer to the site, the quantity of doses of drug required is less. 3) It is easy route of administration of drug for those patients like babies

and

children

who

normally

resist

to

oral

route

of

administration. 4)

It is the only possible route of administration of drug for unconscious patients.

5) The absorption of drug from gastrointestinal tract is not assured by patients

suffering

from

gastrointestinal

disorder

and

hence

parenteral route of administration is preferred. 6) Parenteral route of administration is preferred for those suffering from gastrointestinal disorders like acidity, loss of appetite, etc. 7) The certainty of maintenance of the prescribed dosage of drug is possible in parenteral! route of administration. 8)

There is no chance of drug getting destroyed or inactivated as by the enzyme in gastrointestinal tract.

Disadvantages of parenteral route of administration: 1)

It is not natural route of administration.

2) It is riot easy route for administration of drug for patients and selfadministration is not possible. 3) It is painful route of administration. 4) Preparation of dosage form for parenteral route of administration requires highly sophisticated instrumentation and condition. 5) The verity of dosage form by which the drugs, an be taken by this route is restricted and are in liquids, solutions and suspensions form. 6) Nursing for administration is required. 7) An allergic reaction of the drug (toxicity) is fast and hence is not safe.

8) It is not economical to the patients.