General features and risks of parenteral routes
Parenteral administration encompasses methods of drug delivery bypassing the gastrointestinal tract. The main advantages are the rapid onset of therapeutic response and precise delivery of the dose into the systemic circulation.
However, such methods require strict adherence to aseptic rules, qualified medical personnel, and consideration of the pharmacokinetic properties of each substance. Errors in choosing the route of administration or execution technique can lead to severe local and systemic complications.
Specifics of intravenous and vascular injections
Intravenous administration ensures the instantaneous achievement of the maximum concentration of the drug in the blood. Among the main limitations and risks are:
- The inability to reverse the drug's effect once it has entered the vascular bed.
- The risk of developing thrombophlebitis and infectious complications.
- The danger of embolism in case of gross violations of the execution technique.
- The impermissibility of subcutaneous or intramuscular administration of agents such as norepinephrine due to instant vasospasm and subsequent tissue necrosis.
Complications of intramuscular and subcutaneous injections
Administration of drugs into muscle tissue or subcutaneous adipose tissue is accompanied by the risk of local damage:
- Occurrence of pronounced pain in the injection area.
- The risk of traumatizing major nerve trunks with the needle.
- Formation of painful infiltrates and purulent abscesses if aseptic rules are violated.
- Limitation on the volume of the injected solution (for the subcutaneous method — no more than 2 ml).
Prevention of complications in local anesthesia
Special attention is paid to performing infiltrative and regional anesthesia using local anesthetics, for example, articaine or lidocaine. To prevent accidental entry of the solution into a blood vessel, performing an aspiration test is mandatory before administering the full dose.
Intravascular injection of an anesthetic with a vasoconstrictor causes a sharp increase in blood pressure and an increased heart rate, which poses a threat to the patient's life.
Parenteral means bypassing the GI tract: into a vein, muscle, or under the skin. The rule of three S's: sterility, speed, dose compliance.
Class and exam questions
Why is an aspiration test mandatory before regional anesthesia?
The test is necessary to rule out accidental entry of the local anesthetic into the lumen of a blood vessel. Intravascular injection of a drug with a vasoconstrictor can cause a sharp spike in blood pressure and tachycardia.
What are the main disadvantages of intravenous drug administration?
Key disadvantages include the inability to reverse the drug's effect after injection, the need for strict sterility and qualified personnel, as well as the risk of thrombophlebitis and embolism.
Why is norepinephrine contraindicated for subcutaneous or intramuscular administration?
Due to its pronounced vasoconstrictive action, the drug causes a powerful local vascular spasm, which leads to soft tissue necrosis.
What else to study on this topic
- Pharmacokinetics and bioavailability via various routes of administration
- First-pass hepatic effect and its clinical significance
- Characteristics of depot forms and oil solutions
- Comparative profile of amide-group local anesthetics
- Toxic and allergic systemic reactions during injections
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