routes of drug administration compiled by sarafadeen adebayo, ph.d. thursday, january 07, 20161

ROUTES OF DRUGROUTES OF DRUG

ADMINISTRATION ADMINISTRATION

Compiled by

Sarafadeen Adebayo, Ph.D.

Friday, April 21, 2023 1

ObjectivesObjectives

Friday, April 21, 2023

To describe the various routes of drug administration

Relate dosage forms and route of absorption to the potential rapidity of absorption/therapeutic activity.

To understand the advantages and disadvantages of the various routes of drug administration

2

Buccal/SublingualBuccal/Sublingual

Buccal or sublingual dosage form enable drugs to be taken as smaller tablets held in the mouth or under the tongue.

Buccal tablets are often harder tablets [4 hour disintegration time], designed to dissolve slowly.

Nitroglycerin, as a softer sublingual tablet [2 min disintegration time] may be used for the rapid relief of angina.

This ROA is also used for some steroids such as testosterone and oxytocin while nicotine-containing chewing gum may be used for cigarette smoking replacement.


Advantages of buccal Advantages of buccal sublingual administration:sublingual administration: First pass - The liver is by-passed thus

there is no loss of drug by first pass effect for buccal administration. Bioavailability thus is higher.

Rapid absorption - Because of the good blood supply to the area absorption is usually quite rapid.

Drug stability - pH in mouth relatively neutral (cf. stomach - acidic). Thus a drug may be more stable.


DisadvantagesDisadvantages

Holding the dose in the mouth may be inconvenient.

If any is swallowed that portion must be treated as an oral dose and subject to first pass metabolism.

Small doses only can be accommodated easily.


RectalRectal

Most commonly used for suppository or enema.

Some drugs given by this route include:◦ aspirin,

◦ dipyrone,

◦ paracetamol

◦ theophylline

◦ Chlorpromazine

◦ some barbiturates


Merits & Demerits of Rectal Merits & Demerits of Rectal Administration??Administration??

…………

…………..

…………….

………………


Some Parenteral Routes of Some Parenteral Routes of AdministrationAdministration


IntravenousIntravenous

Drugs may be given into a peripheral vein over 1 to 2 minutes or longer by infusion.

Rapid injections are used to treat epileptic seizures, acute asthma, or cardiac arrhythmias


Advantages of IVAdvantages of IVRapid - A quick response is possible

Total dose - The whole dose is delivered to the blood stream. Large doses can be given by extending the time of infusion.

Veins relatively insensitive to irritation by irritant drugs.


Demerits of IVDemerits of IV

Suitable vein may be difficult to locate.

May be toxic - Because of the rapid response, toxicity can be a problem with rapid drug administrations ◦ could then be given as an infusion while

monitoring for toxicity.

Requires trained personnel

Expensive - Sterility, pyrogen testing and larger volume of solvent means greater cost for preparation, transport and storage.


SubcutaneousSubcutaneous

This involves administration of the drug dose just under the skin.


Advantages: Advantages: Can be given by patient, e.g. in the

case of insulin

Absorption slow but usually complete.

◦Absorption rate can be improved by massage or heat.

◦Vasoconstrictor may be added to reduce the absorption of a local anesthetic agent, thereby prolonging its effect at the site of interest.


Disadvantages: Disadvantages: Can be painful

Irritant drugs can cause local tissue damage

Maximum of 2 ml injection thus often small doses limit use.


IntramuscularIntramuscular

Injection administered into the:

◦deltoid muscle of the buttock or

◦gluteal muscle of the upper arm.


Advantages: Advantages: Larger volume, than sc, can be given by IM

A depot or sustained release effect is possible with IM injections, e.g. procaine penicillin


Disadvantages: Disadvantages: Trained personnel required for

injections.

◦The site of injection will influence the absorption, generally the deltoid muscle is the best site

Absorption is sometimes erratic, especially for poorly soluble drugs, e.g. diazepam, phenytoin.

The solvent maybe absorbed faster than the drug causing precipitation of the drug at the site of injection.


InhalationInhalation

Drugs administered as fine particles of liquids or solids or as aerosols or spray.

The drug may be required for local or systemic effects.

Local effect - bronchodilators

Systemic effect - general anesthesia


MeritsMeritsRapid absorption, by-passing the liver

Absorption of gases is relatively efficient, however solids and liquids are excluded if larger than 20 micron and even then only 10 % of the dose may be absorbed.


Example of Drugs Example of Drugs administered by inhalation administered by inhalation into the lungsinto the lungs

Drugs CommentsCorticosteroids Beclomethasone dipropionate, betamethasone valerate &

triamcinolone acetonide used for relief of brochial asthma

Ergotamine tartrate

Available as a pressurized aerosol preparation & provides relief from migraine much faster than from oral preparations

Sympathomimetics

Fenoterol, rimiterol, salbutamol, salmeterol, & terbutaline are well absorbed from the lungs giving early relief from asthmatic attack.

Sodium cromoglycate

Well absorbed from the lungs when administered as a fine powder or spray but poorly absorbed from the gastro-intestinal tract. Inhalation of the powder may cause bronchospasm; isoprenaline may be administered concurrently to minimize this effect.Friday, April 21, 2023 20

TopicalTopicalLocal effect - eye drops, antiseptic, sunscreen, callous removal, etc.

Systemic effect - e.g., nitroglycerin ointment.

Absorption through the skin, especially via cuts and abrasions but also intact skin, can be quite marked.


Other Routes of Other Routes of AdministrationAdministrationIntra-nasal - some systemic

absorption has been demonstrated for propranolol and some low dose hormones

Intra-arterial for cancer chemotherapy to maximize drug concentrations at the tumor site

Intrathecal directly into the cerebrospinal fluid.


***END OF ***END OF PRESENTATION***PRESENTATION***

QUESTION/DISCUSSION SESSION


routes of drug administration compiled by sarafadeen adebayo, ph.d. thursday, january 07, 20161

Documents

drug dose

rapid absorption

buccal administration

rapid drug administrations

loss of drug

route of absorption

rapid response

area absorption