ROUTE OF DRUG ADMINISTRATION (Part 1/3 )

Introduction:

The route of drug administration is determined primarily by the properties of the drug i.e.

• Water or lipid solubility
•  ionization and by the therapeutic objectives i.e.the desirability of a rapid onset of action
• The need for long-term treatment
• Or restriction of delivery to a local site.

Major routes of drug administration

Routes Of Drug Administration

 

There are four major routes of drug administration which are,

1. Enteral route
2. Parenteral route
3. Topical route
4. Pulmonary or inhalation route

1) Enteral route:

• It’s the most common and oldest method.
• Drug is absorbed in to the systemic circulation through the oral or gastric mucosa, small intestine or rectum.

Types of Enteral route:

Enteral routes include

a)Oral route

b)Sub-lingual route

A) Oral route:

Oral Route

 

• Oral route is the most common route of drug administration.
• It is mostly used for the neutral drugs.
• It may be in the form of tablets, capsules, syrup, emulsions or powders.

Merits:

• Giving a drug by mouth provides many advantages to the patient. Such as
• Oral drugs are easily self-administered.
• Cheapest and economical.
• Irritant drugs which can not be given by parenterals can be given by this route.
• Larger quantity of drug can be given.
• Suitable for producing local action for git e.g. Ant acid
• Toxicities and overdose by the oral route may be overcome with antidotes, such as activated charcoal.
• The drugs preparations need no sterilization.

Demerits:

• Oral route also has some disadvantages, such as
• Drug action has slower onset so not suitable in case of emergency.
• Unpleasant taste of some drugs.
• Unable to use in unconscious patient.
• The pathways involved in oral drug absorption are the most complicated, and the low pH of the stomach may inactivate some drugs.
• Drugs that destroy in git cannot be used e.g. Insulin
• It might cause discoloration of teeth e.g. Iron causes staining, tetracycline’s below 14 cause brown discoloration so are not advisable during pregnancy.

B) Sub-lingual route:

Sub-Lingual Route

• Placement of drug under the tongue allows a drug to diffuse into the capillary network and therefore, to enter the systemic circulation directly.The drug should be lipid soluble and small
• Examples of drugs given by this route include nitroglycerin, iso-prenaline and oxytoxin.  
• Nifedipine used for the treatment of hypertension in emergency is given by sub-lingual rout

Merits:

Sub-lingual administration has several advantages, including

• Drugs do not go in to the hepatic circulation. 
• Convenience of administration.
• Maximum therapeutic concentration can be achieved rapidly
• Low incidence of infection.

Demerits:

Sub-lingual administration of drug has following disadvantages.

• This method is inconvenient.
• Person may swallow the drug
• Might be unpleasant in taste.
• Repeated use of this process may damage the oral mucosa.

TO BE CONTINUED...