Question

2. Brainstorm a list of variables that affect drug actions. Separate the list into two categories: drug-related variables and client-related variables. 3. Identify the pharmacodynamics and pharmacokinetic changes related to age in older adults. Identify the physiologic changes associated with increased age related to pharmacokinetics.

Answer 1

2 . Drug action :

A substance that used to treat an illness , relieve a symptom or modify a chemical process in the body for a specific purpose is called a drug. Action of a drug is influenced by many factors such as body weight, age, drug tolerance, drug interaction, pharmaceutical preparations , genetics, nutritional status etc. These factors can be categorized into drug related variables and client related variables.

Drug related variables:

* Drug interactions ; Pharmaco dynamics and pharmaco kinetics of a drug can be modified by the interaction with another drug, when consuming it together. ( examples: Diuretics increase digitalis toxicity)

* Pharmaceutical preparations: The drug preparation, dosage of each components may affect the drug action.

* Drug administration: Speed and intensity of drug response is depended on the route of administration of drug ( use parenteral route for speedy action)

Client related variables:

* Age; Age is one of the main client related variables. One has to consider the age of the patient, when prescribing the medication and the dose. ( example: Infants and neonates are having delayed gastric emptying and decreased intestinal motility, need more time to achieve optimum plasma concentration of the drug)

* Body size: Concentration of drug attained at the site of action can be influenced by body size

* Genetic factors : drug meyabolism enzyme pattern are controlled by genetic of an individual and it may different from one person to another person

* tolerance and resistance

* Pregnancy and lactation: drugs should be avoided as far as possible during pregnancy and lactation as it may cross the placental barrier and cause teratogenic and pharmacological effects in embryo.

* Disease; Different disease may affect the drug action such as GI disorders ( may alter the absorption of ingested drugs), Liver disease ( metabolism of drug can be altered) , Kidney disease ( drug excretion can be decreased )

3. Pharmaco dynamic and pharmaco kinetics changes related to age in older adults:

Pharmacokinetic changes

* Delay in absorption and gastric emptying

* Serum albumin reduction in elderly ( Serum albumin binds with many drugs ), it may alter the distribution of drug

* decreased liver blood flow and hepatic function( alcoholism) may cause alteration in metabolism,

* Impaired renal function in the elderly, causes reduced excretion of the drug ( pharmaco kinetics) , in turn may leads to increased toxic response

Pharmaco dynamics:

Tolerance: Repeated usage of a drug, eventually cause a need of higher dose to produce the same previous effect. Elderly may have tolerance to certain drugs due to continuous use of a particular drug.