Absorption of medications injected into the subcutaneous tissue or muscle tissue is all influenced by the same factors. However, intramuscular injections are absorbed faster than subcutaneous injections because muscle tissue has a greater blood supply than the tissue just under the skin. Also, muscle tissue can hold a larger volume of medication than subcutaneous tissue. For example, you should not inject more than 1ml (100 units) of injectable medicine into the fat tissue because you will have a knot-like-ball for days at a time. In the end, the form of administration all depends on the base-substance of the medication (water or oil) to determine the speed of delivery. Here is what you need to know when injecting water base or oil base medications.
Intramuscular tissue “muscle tissue” is hydrophilic, meaning it mixes or dissolves with water. Oil-based medications like injectable testosterone, amino acid formulas, and some injectable vitamins (B-complex & Vitamin D) are commonly injected into the muscle for this reason. Since they are oil-based, the muscle tissue rejects the oil, helping them get into the blood faster and effectively. These medications can also be administered into the fat, but as stated before, they might leave a knot in your fat or leave you with a stinging sensation for days.
We find the IM is a better route.
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