Drug Interactions PDF

Drug Interactions Assist.Prof.Dr. Nevzat Birand- [email protected] Drug Interactions Medicines help us feel better and stay healthy. But sometimes drug interactions can cause problems.  HOW DOES DRUG INTERACTION OCCUR??? **An interaction can occur when the effects of one drug are c...

Drug Interactions Assist.Prof.Dr. Nevzat Birand- [email protected] Drug Interactions Medicines help us feel better and stay healthy. But sometimes drug interactions can cause problems.  HOW DOES DRUG INTERACTION OCCUR??? **An interaction can occur when the effects of one drug are changed by the presence of other drugs, herbs, food, drink. **Drug interaction is defined as the pharmacological activity of one drug is altered by the concomitant use of another drug or by the presence of some other substance.  HOW DOES DRUG INTERACTION OCCUR??? ***Drug interactions occur when patients frequently take more than one drug. They may take multiple drugs because of ✓ a single disorder ✓ multiple disorders ✓ OTC (Over The Counter) They may take caffein, nicotine, alcohol, herbal medicine and drugs concurrently. Factors contributing to drug interactions; Multiple drug therapy (Polypharmacy) Multiple prescribers. Multiple pharmacological effects of the drug. Multiple diseases (Hepatic diseases, Renal diseases) Poor patient compliance. Advancing the age of the patient. Drug-related factors. There are three types of drug interactions. (1)Drug-Drug Interactions (2)Drug-Food Interactions (3)Drug-Diseases Interactions (1)Drug-Drug Interactions Drug-drug interactions occur when two or more drugs react with each other. It’s the most common type of interactions. This drug-drug interaction may cause minor or severe or unexpected side effects. For example, If a patient takes pain-killer medication and antihistamine medication, at the same time, the patient can observe more drowsiness effects due to the drugs' side effects. (2)Drug-food interactions Food can cause clinically important changes in drug absorption which can happen in the Gastrointestinal (GI). Therefore, certain drugs should not be taken with certain food. Food frequently decreases the rate of drug absorption. (2)Drug-food interactions Medications can interact with foods. For example, Grapefruit juice Kiwi Pomegranate Green tea Sage tea Milk products Alcohol EX: Tetracycline is an oral antibiotic in the tetracyclines family of medications. Calcium containing foods (milk, cheese and other dairy foods) Calcium is Insoluble and Unabsorpable complex Tetracycline+Calcium Impact: Absorption reduce and Antibacterial effects may be lost. EX: Grapefruit juice is an inhibitor of CYP3A4 in the liver and intestinal wall. Grapefruit juice can inhibit the metabolism of certain drugs, thereby raising blood levels. Grapefruit juice can increase the blood levels of atorvastatin. EX:Food may also (rarely) have direct impact on drug action Foods rich in Vitamin K (broccoli, Brussels sprouts, cabbage) can reduce the effects of warfarin. Vitamin K may reduce the effectiveness of warfarin. warfarin acts by inhibiting Vitamin K-dependent clotting factors. (3) Drug-Disease Interactions Drug interactions don’t always occur with just other drugs or foods. A medical condition can impact the way a drug works. For example; Over-the-counter oral decongestants like pseudoephedrine may increase blood pressure and can be dangerous if patient have high blood pressure *** Drug interactions can cause increased costs in healthcare. *** A serious drug interaction could result in injury, hospitalisation, or rarely, death. ***Not all drug interactions are bad*** Mechanisms of Drug Interactions Drug interactions can be related to the following mechanisms: ✓ Pharmaceutical interactions ✓ Pharmacokinetic interactions ✓ Pharmacodynamic interactions ***An interaction occurs when pharmacokinetics or pharmacodynamics of drug are changed. ***Sometimes the drug interaction can be caused by more than one mechanism, although usually only one mechanism is more significant. Pharmaceutical interactions **Interactions that occur prior to systemic administration. For example: Incompatibility between two drugs mixed in an IV fluid. These interactions can be physical (e.g. with a visible precipitate) Pharmacokinetics Interactions Pharmacokinetics is ‘what the body does to the drug’. ✓ One drug alters the rate or extent of absorption, distribution, metabolism or excretion of another drug. ✓ A change in blood concentration causes a change in the drug’s effect (the so-called ADME interactions).  Alterations in absorption Drug absorption may be enhanced or reduced by drug interaction EX: Ketoconazole is an anti-fungal medication that is used to treat certain infections caused by fungus. Ketoconazole +Antacids Proton Pump Inhibitors H2 receptor blockers Impact: Antacids, Proton Pump Inhibitors and H2 receptor blockers can decrease the absorption and blood levels of ketoconazole and make the medication less effective against fungal infections. Therefore, these drugs must be separated by at least 2 hours at the time of administration of both. EX: A-Digoxin (AF, HF)- 40% or more of the administered dose is metabolised by the intestinal flora. B-Antibiotics kill a large number of the normal flora of the intestine Digoxin+Antibiotics Impact: Increase digoxin concentration and increase its toxicity. Pharmacodynamic Interactions Pharmacodynamic drug-drug interactions (DDIs) occur when the pharmacological effect of one drug is altered by that of another drug in a combination regimen. If drug A and drug B are both toxic to the same organ, taking them together will cause more injury than if they were not combined. Ex. Isoniazid and rifampin are hepatotoxic. Drug Interactions Categories Each Interact monograph is assigned a risk rating of A, B, C, D, or X. Or It is sometimes shown that Major, Moderate or Minor interaction. Drug Interactions Data have not demonstrated either pharmacodynamic or pharmacokinetic A No Interaction interactions between the specified agents Data demonstrate that the specified agents may interact with each other, but there is little to no evidence of clinical concern resulting from their B No action needed concomitant use. Data demonstrate that the specified agents may interact with each other in a clinically significant manner. The benefits of concomitant use of these two medications usually outweigh the risks. An appropriate C Monitor therapy monitoring plan should be implemented to identify potential negative effects. Dosage adjustments of one or both agents may be needed in a minority of patients. Data demonstrate that the two medications may interact with each other in a clinically significant manner. A patient- specific assessment must be conducted to determine whether the benefits of concomitant therapy outweigh the risks. D Specific actions must be taken in order to realize the benefits and/or minimize the toxicity resulting from concomitant Modify regimen use of the agents. These actions may include aggressive monitoring, empiric dosage changes, choosing alternative agents Avoid Data demonstrate that the specified agents may interact with each other in a clinically significant x combination manner. The risks associated with concomitant use of these agents usually outweigh the benefits. These agents are generally considered contraindicated. Drug Interactions Drug Interactions ***alprazolam: management of anxiety disorders, specifically panic disorder or generalised anxiety disorder ***Ramipril:Anti-hypertension Drug Interactions Drug Interactions Drug Interactions Drug Interactions Drug Interactions ***This is for Turkish Students ***This is for Turkish Students Drug Interactions- Practice Course Drug Interactions- Practice Course Drug Interactions- Practice Course Drug Interactions- Practice Course Drug Interactions- Practice Course