Pharmacokinetic and pharmacodynamic drug interactions
- 1. PRESENTED BY :- SAJAL KUMAR CHOWDHURY B. PHARM 4TH YEAR
- 2. Introduction Classification Absorption interactions Distribution interactions Metabolism interactions Elimination interactions References
- 3. A drug interaction is an interaction between a drug and some other substance , such an another drug or a certain type of food , which leads to interaction that could manifest as interaction or decrease in the effectiveness Mostly undesirable Rarely desirable The drug whose activity is effected by such an interaction is called as a Object drug . The agent which precipitate such as interaction is referred to as the Precipitant .
- 4. Altered concentration , pharmacokinetic drug interactions occur when one drug changes the systemic concentration of another drug , altering how much and for how long it is present at the site of action
- 5. Altered effect pharmacodynamic drug interactions occure when interacting drugs have either additive effects , in which case the overall effect in increased or opposing effect , in which case the overall effect is decreased or even cancelled out .
- 6. Absorption interactions Distribution interactions Metabolism interactions Excretion interactions
- 7. Absorption interaction are those where the absorption of the object drug altered . Since the oral route is one , most frequently used to administer drugs , interactions influencing absorption are more likely to occur within the gastrointestinal tract The net effect of such an interaction is Faster or slower drug absorption . More or less drug absorption.
- 8. Drug distribution interactions are those where the distribution pattern of the subject drug is altered. The major mechanism for distribution interaction is alteretion in protein – drug binding . Many drugs interact by displacement of each others binding to plasma proteins. Acidic drugs are known to have an affinity to bind to plasma proteins ,hence when two or more are given concomitantly ,competetive binding for the same site or receptor may displace one drug from the protein binding site increasing the amount of the displaced free drug in plasma and verious tissues
- 9. Certain drugs stimulation the activity of hepatic microsomal enzymes. This effect is referred as enzyme indication The increase activity is due to enhanced enzyme synthesis results in increased amounts of drug metabolizing enzyme Enzyme induction will result in increased metabolism and excretion and reduced effect of agent which is metabolised by the hepatic enzymes Eg : Warfarin and Phenobarbitol
- 10. Drug elimination reactions are those where the excreation pattern of the object drug is altered The major routes for elimination the drugs remain kidney and bile , but there are no significant drugs- drug interactions through bile elimination , but only drug – disease ones . Some drugs are excreted from the body unchanged in the active form usually in the urine or via the biliary tract in the faeces.
- 11. D.M. Barahmankar , S.B.Jaiswal Biopharmaceutics and pharmacokinetics , Vallabh Prakashan , Second edition P. No. 224- 233 Prativa Nand , R.K. Khar, Hospital and Clinical pharmacy .. Birla Publication , Thirteenth edition , P.no. 270-280
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