DrPrashant June - 30 - 2010 pharmacodynamics

by  Falguni Khanderiya

One or more of the following categories of differences among the individuals responsible for variation:-

  1. individuals differ in pharmacokinetic handling of drugs.
  2. variation in number or state of receptors.
  3. variation in neurogenic concentration of specific constituents.

Factors modifying drug action either

1. Quantitatively-depend on plasma concentration

2. Qualitatively-depend on drug allergy or idiosyncrasy.

Various factors are:-

1. Body size-

Individual dose=BW (kg)/70 * avg adult dose

2. age-

Dose of drug for children is calculated from adult dose.

Child dose=age/age+12 *adult dose

Some drugs of low safety margin when given in higher concentration cause kernictrus (sulfa) ,/Chloramphenicol may produce gray baby syndrome.

3. sex-

Females have lower body size and require less dose.

Gynaecomastia is a side effect that occurs only in men.

4. SPECIES AND RACE-

Black race requires higher and Mongols require lower concentration of atropine to dilate the pupil.

5. GENETICS-the effect of genetic factors can also vary the response of a drug (pharmacokinetics)

6. ROUTES OF ADMINISTRATION-

Speed and intensity of drug depends on route of drug especially in i.v. and sublingual.

7. ENVIRONMENTAL FACTORS AND TIME OF ADMINISTRATION

8. PSYCHOLOGICAL FACTORS-placebo

9.PATHOLOGICAL STATES-like liver diseases, Kidney diseases, GIT diseases, Congestive heart failure can also alter the response of a drug

10.OTHER DRUGS- given simultaneously can change the response.

Depending on pharmacokinetics and pharmacodynamics of the drugs.

11.CUMULATION-long term administration of a drug can also alter the response.

12.TOLERANCE-

Depends on higher drug dose called as refractoriness.

It is of 2 types-

Natural

Acquired

Natural-in it some individuals are less sensitive to a particular drug.

Acquired-if the patient is given same drug  repeatedly for long time,tolerance is developed

Related Post

Activate the Wp-related-posts plugin to see the related post list!

Comments are closed.

-->
Prof.Dr.Prashant,MD (popularly known as Prashant Sir)is one of the most popular faculties of pharmacology in Index Medical College ,Indore ,MP,Malwa region of India. He is well adored by medical,dental,nursing,physiotherapy,occupational therapy and pharmacy students for his story telling style of teaching pharmacology in clinical settings.Hundreds of his students have cleared pre postgraduate entrance exams,in flying colors, remembering his mnemonics of pharmacology .This Website is his latest en-devour to simplify the difficulties faced by students especially those who find pharmacology a bit difficult. If you ever feel ,that you/Your child is benefited by this website,or by Dr Prashant\'s Unique teaching,if you support the cause of this website then you can deposit any amount as Gurudakshina/charitable Donation to SBI AC 32346197847 and sms us at 09826247595 or email at drprashantw@gmail.com.Your contribution will be highly appreciated.-Editor