Different Types of Injections
In medicine, there are many ways to get drugs into the human body, in addition to the most familiar oral methods, injections can also be done. In fact, drug injection can be divided into several ways, mainly intravenous, subcutaneous and muscle injection methods. Usually absorbed by the subcutaneous or muscular injection site is simply diffusion, via microvascular membranes into the blood circulation. The absorption rate is related to the area of the absorbed microvascular membrane and the solubility of the drug in Interstitial Fluid.
Intravenous injection is a method of medicine dissolving in aqueous solutions and injecting the solution directly into the vein. The required blood concentration can be reached immediately and correctly after injection, so the efficacy of the drug appears quickly, and it can be used in emergency cases. However, when barbiturates are used as a venous general anesthetic, the dose cannot be predicted in advance and can only be adjusted to the patient’s response. The risk of intravenous injection is high, not only can side effects occur, and drugs cannot be excluded immediately after injection.
Subcutaneous administration, the absorption of the drug is uniform and slow, and can maintain a long time of action. Drugs must not be irritating to the skin, otherwise they may cause severe pain, necrosis and decay. The absorption rate of the drug is injected subcutaneous, which can change the absorption of the drug in some ways to prolong its efficacy. If the absorption of insoluble essence protamine insulin suspension is slower than soluble insulin; vasoconstrictor is added to local anesthesia can also extend the duration of action; for example, sex hormones, paradrenal cortex, etc. are made into pellets, planted under the skin, called Implantation which is extremely absorbed slowly resulting in a long-term persistence effect for weeks to months.
Water-soluble drugs are absorbed quickly after Intramuscular injection, but the absorption of oil-soluble or suspension agents is slower. Due to the low number of muscle sensory nerves and retardation, any irritating drugs that are not suitable for subcutaneous injection may be performed by muscle injection.
Drugs are injected directly into the arteries to limit their action on specific tissues or organs. Diagnostics are sometimes administered with arterial injection. Mainly used for blood transfusion, suitable for critical conditions, the injection site usually selects radial arteries, humeral arteries.
Other chemotherapy for local cancer (appropriate arteries to supply blood to the site of the cancer), ischemic cerebrovascular lesions (carotid artery), arteriosclerosis occlusion and deep venous thrombosis of the lower extremities (selected strands arteries) and so on.
Most of the pain is controlled in traditional ways, but some of the pain is caused by systemic opium use or persistent pain; due to the Blood-brain barrier, and Blood-cerebrospinal fluid Barrier which often prevent drugs from entering the central nervous system. Therefore, when the drug is intended to act locally or rapidly on the meninges or cerebrospinal axis, it is necessary to inject the drug directly into the subspinal spider cavity (e.g. lumbar anesthesia) to produce a drug effect.
The abdominal cavity has a wide absorption surface, so the drug enters the circulation quickly after injections from the abdominal cavity. Abdominal injections are commonly used in animal experiments, but are clinically used occasionally.