Drug action duration

Fhtients with kidney disease may exhibit drug toxicity and a longer duration of drug action. The dosage of drugp may be reduced to prevent the accumulation of toxic levels in the blood or further injury to the kidney. 

Drug Dose Onset of Action Duration of Action Adverse Effects 1 Special Indications... 

The Army, however, was now attempting for the first time to develop trustworthy estimates of how various doses of a given drug would affect populations, rather than single individuals. This required the establishment of parameters - numbers that would define the most probable quantitative clinical effects across a spectrum of subjects. Commanders would need to know not only the typical but also the probable range of response values for such important attributes as potency, time of onset, duration and other important aspects of drug action. Such precision is rarely called for in civilian settings (except in, e.g., cancer therapy). 

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. 

Excretion, along with metabolism and tissue redistribution, is important in determining both the duration of drug action and the rate of drug elimination. Excretion is a process whereby drugs are transferred from the internal to the external environment, and the principal organs involved in this activity are the kidneys, lungs, biliary system, and intestines. 

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. 

Benzodiazepines are ciassified as short, medium, and iong acting. This reiates to the duration of drug action in the body. Length of action can aiso be infiuenced by the heaith of the patient s iiver and the patient s age and weight. ... 

Despite many clinical similarities, these agents differ in their absorption, dosing with other drugs, and duration of actions for example, quinapril has a of 3 hours whereas ramipril has a of 13-17 hours. The quest for ACE inhibitors devoid of the sulfhydryl group also led to the evaluation of phosphonate-containing inhibitors, on the basis of the notion that phosphinic acid is bioisosterically equivalent to sulfhydryl and carboxylate groups in terms of Zn " chelation. This lead to the development of fosinopril... 

For a patient in severe pain, the administration of an opioid analgesic is usually considered a primary part of the overall management plan. Determining the route of administration (oral, parenteral, neuraxial), duration of drug action, ceiling effect (maximal intrinsic activity), duration of therapy, potential for adverse effects, and the patient s past experience with opioids all should be addressed. One of the principal errors made by physicians in this setting is failure to adequately assess a patient s pain and to match its severity with an appropriate level of therapy. Just as important is the principle that following delivery of the therapeutic plan, its effectiveness must be reevaluated and the plan modified, if necessary, if the response was excessive or inadequate. 

Remmer H. In Brodie BB, Erdos EG, eds. Metabolic Factors Controlling Duration of Drug Action, Proceedings of First International Pharmacological Meeting, Vol. 6. New York Macmillan, 1962. 

In the absence of drug, a series of high-frequency repetitive action potentials filled the entire duration of the current pulse. Phenytoin, carbamazepine, and sodium valproate all markedly reduced the number of action potentials elicited by the current pulses. (Modified and reproduced, with permission, from Macdonald RL, Meldrum BS Principles of antiepileptic drug action. In Levy RH, et al [editors]. Antiepileptic Drugs, 4th ed. Raven Press, 1995.)... 

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