Deltoid muscle, blood flow

The name of this route means within the muscle. Intramuscular injection requires a deeper penetration than the subcutaneous method but is associated with a faster absorption rate when the drug is prepared in a water solution and there is a good rate of blood flow at the site of administration. Absorption rates may differ depending on the rate of blood flow to the muscle group the drug is injected into in practice, the most common muscle sites are the deltoid, thigh, and buttocks. The absorption rate can also be modulated by the solution that the drug is prepared in fV>r administration. 

Drugs in aqueous solution are absorbed rapidly following intramuscular (i.m.) injection, although this varies depending on factors such as the blood flow to the injection site. In humans, absorption from the deltoid or vastus lateralis muscles is faster than from the gluteus maximus. Absorption from this site is slower in females than in males. This has been attributed to sex differences in the distribution of subcutaneous fat, since fat is a relatively poorly perfused tissue. 

The absorption rate after intramuscular administration differs depending on type of muscle chosen. Studies have shown that intramuscular injections result in different plasma concentrations of narcotics and perceived pain relief depending oti the type of muscle used for administration. This was also found for the response to vaccination and use of antibiotics and insulin [7]. Absorption of active substances from the intramuscular site depends mi the quantity and composition of the connective tissue and the rate of vascular perfusion of the area. Blood flow in the muscles varies (it is increased in deltoid muscle) and is influenced by the exercise of the muscle and morbidity. The muscles are covered with the subcutaneous connective tissue, a hpid layer (adipose layer) and the skin. The thickness and the Upid content of these tissues are different in different body areas. The subcutaneous fat layer at the gluteal intramuscular injection site is thicker in females (mostly > 3 cm) than in males. The medication should be administered with a needle long enough to reach the muscle without penetrating underlying structures. 

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