Drug action administration

Intravenous administration of a drug produces the most rapid drug action. Next in order of time of action is the intramuscular route, followed by the subcutaneous route Giving a drug orally usually produces the slowest drug action. 

Discuss the uses, general drug action, contraindications, precautions, interactions, and general adverse reactions associated with the administration of the antitubercular drugs. 

The Effect of Route of Administration and Distribution on Drug Action... 

Nanoparticles show great promise as devices for the controlled release of drugs, provided that the choice of material for nanoparticle formation is made with the appropriate considerations of the drug cargo, administration route, and the desired site of action. The use of nano- and microparticles as controlled drug-delivery devices has recently been extensively reviewed [97]. 

The terminator of drug action is, of course, elimination. Elimination is a composite of excretion (kidney, etc.) and biotransformation (metabolism). The primary measure of drug elimination from the whole body is clearance, CLt, defined as the volume of plasma fluid removed of drug per unit time. It is a direct measure of the loss of the drug from the system and can be calculated from Eq. (3.5) after IV administration of a dose of the drug. 

The provision of optimal drug action from topical administration sites (such as ointments, creams, transdermal patches, ophthalmic, ear, and nasal preparations)... 

To demonstrate this statistically, Phil Kysor and I compiled the intercorrelations among the 12 tasks at various experimental times (Fig. 42). Statistically, the matrices shown above simply demonstrate that the variance in scores are progressively accounted for by intensity of dmg effects. Thus, one can predict individual impairment in all skill areas by the degree to which drug action affects performance in any single task. This applies, incidentally, to individuals who may be quite dissimilar in various abilities prior to the administration of a belladonnoid drug such as EA 3580. 

PK/PD models are obtained by combining a PK model (Section 13.2.4) and a PD model (Section 13.2.5), allowing the quantification of the relationship between drug administration and drug action. The principles of PK/PD modelling will be dealt with briefly. For a more detailed treatise, some excellent reviews can be found in the literature [21]. 

Despite the fact that the present classifications are extremely convenient for practical medical personnel, it should be kept in mind that the duration of drug action—especially of the first three groups of compounds—depends on various factors besides the structure of the compounds, such as drug form, method of administration, pathology for which the drug is being used, general treatment time, etc. 

Advantages of the intramuscular and subcutaneous routes include an increased reliability and precision in the drug blood level Anally achieved and reasonably rapid absorption and onset of drug action. There are, however, serious disadvantages as well. Pain, tenderness, local tissue necrosis (primarily with highly alkaline injections), microbial contamination, and nerve damage may be associated with these forms of parenteral administration. 

Heparin is prescribed on a unit (lU) rather than milligram basis. Tlie dose must be determined on an individual basis. Heparin is not absorbed after oral administration and therefore must be given parenterally. Intravenous administration results in an almost immediate anticoagulant effect. There is an approximate 2-hour delay in onset of drug action after subcutaneous administration. Intramuscular injection of heparin is to be avoided because of unpredictable absorption rates, local bleeding, and irritation. Heparin is not bound to plasma proteins or secreted into breast mUk, and it does not cross the placenta. 

The most commonly used vasoconstrictors, the sympathomimetic drugs, are often added to local anesthetics to delay absorption of the anesthetic from its injection site. By slowing absorption, these drugs reduce the anesthetic s systemic toxicity and keep it in contact with nerve fibers longer, thereby increasing the drug s duration of action. Administration of lidocaine 1% with epinephrine results in the same degree of blockade as that produced by lidocaine 2% without the vasoconstrictor. 

The pharmacological agents useful in this disorder may be grouped under five broad categories of treatment (Table 64.2). Such a classification system takes into account the mode of drug action, the route of administration, and the means by which target organ selectivity is achieved. 

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