Injections

1860s,

Parenteral

Indications

Therapeutic reasons

More rapid effect and higher serum levels than orally

Drugs affected by digestive enzymes in the gut eg. insulin

May be used for drugs not absorbed orally eg. hydroxycobalamin

May be given to patients unable to take oral medication eg. glucagon

Enhanced placebo effect

Choice of Route

Intravenous - blood

Intramuscular - muscle

Subcutaneous - subcutaneous tissues

Intradermally - dermis

Locally

Intravenous

Speed of action

Drug is delivered into a systemic vein

High plasma levels

Infusions may be given

Titration of dosages

Painless

Rapid adverse effects

Intramuscular

Skeletal muscles well perfused

Relatively few pain receptors

Up to 5 mls of fluid

1 - 2 mls for deltoid

Some drugs are hazardous to give intravenously

Delayed rate of absorption

Some im preparations may cause embolic complications if given iv

Subcutaneous

Less painful than im

Speed of action slower

Duration of effect longer

Blood supply to adipose layer is poor

Absorption rate is 1 to 2 mls per hour

Problems in shocked or hypothermic patients

Intradermal

Diagnostic indications eg. Heaf test

Vaccines - smaller dose

Sites

Intravenous

Usually established - forearm or back of hand

Young children - scalp vein

Central vein

Intramuscular

Outer aspect of thigh usually into vastus lateralis

Upper outer quadrant of the buttock, into glutamus maximus - avoid superior gluteal artery and sciatic nerve

Upper outer aspect of arm into deltoid muscle - no more than 1 ml

Blood supply to deltoid is 7% greater than vastus lateralis and 17% more than to gluteal muscle

Subcutaneous

Upper outer aspect of arm

Outer aspect of thigh

Abdomen

Almost any site is possible

Intradermal

As for subcutaneous - forearm is also used

Potential complications for patients

A degree of muscle damage is inevitable with im

0.4% of people developed local complications after an im

Muscle damage - needle myopathy and focal myopathy

Needle myopathy - minimised by good technique and optimum sized needle

Focal myopathy is related to type of preparation and the volume injected

Preparations with a near neutral pH and delivered in water - based solvents cause the least muscle damage

Small blood vessels damage - post injection bruising.

Infection

Locally infection - abscess formation

Possible anaerobic pathogens

Strict asepsis

In areas where poor aseptic technique is used injection abscess frequent.

Systemically - potential fatal nosocomial infection

Hepatitis B and C, HIV

With single use equipment and good technique these complications will never occur

Swabbing the site prior to injection is not required

If alcohol is used it should be given time to dry

Allergy

Local or systemic

Prevent, observe, reported, treat

Other complications

Pain

Air introduction

Undue patient anxiety

Fainting

Particulate introduction

Hitting a bone

Skin staining

Patient moves

Potential complications for practitioner.

Needle stick injuries

Encourage bleeding

Soak in iodine

Glass vials - cuts

Splinters of glass flying off into nearby eyes.

Avoid direct contact with preparations

Equipment

Syringes

Hypodermic needles vary in length and diameter

Green (21 G)

Blue (23 G)

Light brown or orange (26 G)