Pharmacodynamics – one of the parts of pharmacology (science of drugs), studying the influence of the body on the drug, i.e. how medicinal substances enter the body, and are absorbed into the bloodstream, are transported to organs and tissues, metabolised and excreted from it. One of the important issues that considering pharmacodynamics – routes of administration of medicines. All routes of administration are divided into integral (via the gastrointestinal tract) and parenteral (bypassing the gastrointestinal tract). And if the first more or less clear, the parenteral administration of drugs raises many questions for patients.
Injection routes of administration
Among the injection paths of the most common are intravenous and intramuscular. Besides them there are also subcutaneous, intradermal, intra-arterial and intraosseous. Let's look at parenteral is like?
Intravenous administration of medicines is perhaps the most common among injections. Combining relative simplicity, it provides rapid delivery of drug to the organs and tissues with 100% bioavailability. Introduction parenteral is as a unique opportunity to deliver minimum volumes of drugs, and to produce-hour infusion using an installed venous catheter and a special device. In addition, the intravenous route is the only method of administration of drugs in critical conditions and in cases when the patient is unconscious, and also gives the ability to enter drugs that are poorly soluble in the gastrointestinal tract.
In addition to all the advantages of intravenous route of administration has its own drawbacks. So, IV can only be entered parenteral means, which is a water solution or suspension is water-based, and in the implementation of manipulation is necessary to avoid the ingress of air into a blood vessel as this can lead to the development of embolism.
Intramuscular injection, at first glance, it may seem equivalent intravenously, but it is not so. In addition to the lower bioavailability, intramuscular injection is not performed in a critical state, because it reduces Central hemodynamics, blood flow to muscle decreases and, consequently, reduced drug delivery. Also intramuscular injection is not administered more than 10 ml of solution.
Intraarterial has found its application in the practice of cardiac surgery and angiology, and diagnostic procedures. In this case, the parenteral introduction of a new breakthrough in medicine, because in this way carry out the introduction, for example, contrast agents for vascular system investigation and determine the scope of further remedial measures. This, in turn, allows new insights on the diagnostic process.
Injecting – how's that?
Among non-injection routes should be noted transdermal, intravaginal, intratracheal, and intranasal.
Transdermal path represents the penetration of drugs through the skin. The path for an adult can cause only a local effect of the administered drug (e.g., in the form of creams or ointments), but the child's drugs can have a systemic effect. This is because a baby's skin has a high sorption capacity, which leads to the penetration of drugs into the bloodstream.
Intratracheal introduction refers to the inhalation pathways. The introduction of the drug occurs through the trachea into the bronchial tree. Typically, this method is the introduction of drugs that affect the respiratory system.
A large spread of intranasal in the form of sprays and drops, and also the application of preparations in the form of drops to the eye.
Which method to choose?
The question of choice is always relevant. If possible use oral the way it should be confined to them, and choosing the parenteral introduction of medicines, you need to focus on the patient's condition, and he injected the drug.
Parenteral drugs are drugs intended for insertion into the human body, bypassing the gastrointestinal tract. The choice of this route of administration should be based on the principles of rationality, but also absolutely necessary for the patient, since in any case, this type of introduction is associated with certain risks.