Anesthetics administration route

Ziconotide is a non-opioid, non-NSAID, non-local anesthetic used for the amelioration of chronic pain. In December 2004 the FDA approved ziconotide for intrathecal administration. The drug is derived from a marine snail toxin. Its mechanism of action has not yet been elucidated. Due to serious side effects or lack of efficacy when delivered through more conventional routes ziconotide must be administered in-trathecally. It s use is considered appropriate only for management of severe chronic pain in patients for whom intrathecal therapy is indicated. 

A most important advantage of ketamine over other anesthetic agents is its potential for administration by the IM route. This is particularly useful in anesthetizing children, since anesthesia can be induced relatively quickly in a child who resists an inhalation induction or the insertion of an IV line. Ketamine has a limited but useful role as an IM induction agent and in pediatrics. 

Reduction of local or regional blood flow is desirable for achieving hemostasis in surgery, for reducing diffusion of local anesthetics away from the site of administration, and for reducing mucous membrane congestion. In each instance, -receptor activation is desired, and the choice of agent depends on the maximal efficacy required, the desired duration of action, and the route of administration. 

Local anesthetic action, also known as "membrane-stabilizing" action, is a prominent effect of several 3 blockers (Table 10-2). This action is the result of typical local anesthetic blockade of sodium channels (see Chapter 26) and can be demonstrated experimentally in isolated neurons, heart muscle, and skeletal muscle membrane. However, it is unlikely that this effect is important after systemic administration of these drugs, since the concentration in plasma usually achieved by these routes is too low for the anesthetic effects to be evident. These membrane-stabilizing 3 blockers are not used topically on the eye, where local anesthesia of the cornea would be highly undesirable. Sotalol is a nonselective 3-receptor antagonist that lacks local anesthetic action but has marked class III antiarrhythmic effects, reflecting potassium channel blockade (see Chapter 14). 

The advantages of administration by intramuscular injection are that the muscle can act as a depot, and the rate of disappearance of drug from the site of injection can be calculated. Inhalational, intranasal, and intratracheal administration are normally reserved for vapors and aerosols including anesthetics. Absorption is facilitated by small-sized particles, high lipid solubility, sufficient pulmonary blood flow, and a large absorptive surface area, as it is present in healthy lungs. Administration by these routes can be very rapid when several of the factors favoring increased absorption are combined. 

General Anesthetics Classification and Use According to Route of Administration... 

Systemic effects are more likely to occur with long-acting anesthetics if an excessive dose is used, if absorption into the blood stream is accelerated for some reason, or if the drug is accidentally injected into the systemic circulation rather than into extravascular tissues.17 40 Other factors that can predispose a patient to systemic effects include the type of local anesthetic administered, as well as the route and method of administration.3 Therapists and other health care professionals should always be alert for signs of the systemic effects of local anesthetics in patients. Early symptoms of CNS toxicity include ringing/buzzing... 

Cocaine acts as a potent local anesthetic and is a strong CNS stimulant it extends and intensifies the effects of dopamine, norepinephrine, serotonin neurotransmitters [3], The effects of cocaine can vary in relation to the individual characteristics, the administered dose, frequency of use, and route of administration. The intranasal administration causes plasma peak concentrations after 5-20 min, the euphoric effect in 15-20 min with a half-life of 40 min. The oral route involves a slow and low absorption with plasma peak concentrations after approximately 90 min and euphoric effect in 15-20 min. Intravenous plasma peak is immediate, euphoric effect occurs after 4-8 min with a half-life of about 40 min. Finally it may be administered through inhalation of combustion products or crack vapors, with great absorption speed. 

Inhalation Inhalation provides the rapid delivery of a drug across the large surface area of the mucous membranes of the respiratory tract and pulmonary epithelium, producing an effect almost as rapidly as by intravenous injection. This route of administration is used for drugs that are gases (for example, some anesthetics), or those that can be dispersed in an aerosol. The route is particularly effective and convenient for patients with respiratory complaints (for example, asthma or chronic obstructive pulmonary disease) as drug is delivered directly to the site of action and systemic side effects are minimized (see p. 219). 

Anesthetized rats are used for testing the side effect potential of a candidate compound on intermediary metabolism in liver, muscle and adipose tissue with subsequent effects on metabolic blood parameters (e.g. glucose, lactate, free fatty acids, triglycerides) and insulin. The use of anesthetized rats represents more a principal assessment of the pharmacological side effect potential since the candidate compound must be administered intravenously or intraperitoneally (enteral/intestinal administration should be avoided due to the anesthesia-induced decrease in intestinal motility with subsequent impairment of enteral absorption), compared to the study in conscious rats in which the candidate compound can be studied after oral administration, which in most cases represents the clinical route of administration for small molecular drugs. 

Since the intravenous administration ensures the maximum exposure especially in case of anesthetized or preoperated animals, this route is often favored. 

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