Intramuscular route

Intramuscular analgesia has the following advantages:

• simple to administer
• relatively cheap compared with other forms of analgesia
• an extended action
• no first-pass metabolism

However, this route also has disadvantages:

• can be painful in itself; rarely, the sciatic nerve may be damaged
• dose is non-titratable
• there is unpredictable absorption, e.g. after exercise
• the extended action may produce dangerous side effects
• infection at the site of injection is an uncommon sequel
• injection may be to an inappropriate site, e.g. to the gluteals producing very slow absorption, subcutaneously in fat people

Drugs given by the intramuscular route include the opiates morphine and papaveretum.