Addiction, Dependence, Tolerance, Allergy.pptx

Drug dependence refers to someone feeling like they cannot function normally without the use of the substance.
It is a state in which use of drugs for personal satisfaction is accorded a higher priority than other basic needs, often in the face of known risks to health.
Drugs capable of altering mood and feelings are liable to repetitive use to derive euphoria.

Psychological dependence
It is developed when the individual believes that optimal state of wellbeing is achieved only through the actions of the drug.
It may start as liking for the drug effects and may progress to compulsive drug use in some individuals who then lose control over the use of the drug.
The intensity of psychological dependence may vary from desire to craving
Physical dependence

It is a sign of addiction.
It is a condition in which a person takes a drug over time, and unpleasant physical symptoms occur if the drug is suddenly stopped or taken in smaller doses.
Discontinuation of the drug results in a characteristic withdrawal (abstinence) syndrome.
It causes adaptation of the nervous system to function normally only in the presence of the drug, hence also called ‘neuroadaptation’
Ex: opioids, barbiturates and other CNS depressants including alcohol and benzodiazepines. (dependence + addiction)
Stimulant drugs, e.g. amphetamines, cocaine produce little or no physical dependence (causes more addiction + less dependence)
ADDICTION

Also called “substance use disorder”
It  is a neuropsychological disorder characterized by a persistent and intense urge to use a drug or engage in a behavior that produces natural reward, despite substantial harm and other negative consequences.
Procuring the drug and using it takes precedence over other activities.
Repetitive drug use often alters brain function and weakens self-control.
Drug addiction increases the levels of dopamine (control the brain’s reward and pleasure centers)
These increased levels of dopamine create feelings of pleasure and euphoria.
Examples of drug addictions include alcoholism, cannabis addiction, amphetamine addiction, cocaine addiction, nicotine addiction, opioid addiction, and etc. 
Effects Of Drug Addiction
Changes in appetite, body temperature and sleeping patterns
Wild mood swings, anxiety, paranoia, depression, and violence
Heart rate irregularities, heart attack
Hallucinations
Confusions
Kidney and liver damage
Abdominal pain, vomiting, constipation, diarrhoea
Seizures, stroke
DRUG ALLERGY

Drug Allergies occur when your immune system reacts to a drug or a metabolite of drug, that usually doesn't cause a reaction in most people.
It is an immunologically mediated reaction producing stereotype symptoms which are unrelated to the pharmacodynamic profile of the drug
Generally occur even with much smaller doses of the drug.
This is also called drug hypersensitivity.
The target organs primarily affected in drug allergy are
Skin, Airways, Blood vessels / Blood and Gastrointestinal tract

1. DRUG DEPENDENCE ADDICTION TOLERANCE TACHYPHYLAXIS IDIOSYNCRACY DRUG ALLERGY

2. DRUG DEPENDENCE Drug dependence refers to someone feeling like they cannot function normally without the use of the substance. It is a state in which use of drugs for personal satisfaction is accorded a higher priority than other basic needs , often in the face of known risks to health. Drugs capable of altering mood and feelings are liable to repetitive use to derive euphoria. Psychological dependence It is developed when the individual believes that optimal state of wellbeing is achieved only through the actions of the drug. It may start as liking for the drug effects and may progress to compulsive drug use in some individuals who then lose control over the use of the drug. The intensity of psychological dependence may vary from desire to craving

3. Physical dependence It is a sign of addiction . It is a condition in which a person takes a drug over time, and unpleasant physical symptoms occur if the drug is suddenly stopped or taken in smaller doses. Discontinuation of the drug results in a characteristic withdrawal (abstinence) syndrome . It causes adaptation of the nervous system to function normally only in the presence of the drug, hence also called ‘neuroadaptation’ Ex: opioids, barbiturates and other CNS depressants including alcohol and benzodiazepines. (dependence + addiction) Stimulant drugs, e.g. amphetamines, cocaine produce little or no physical dependence (causes more addiction + less dependence)

4. ADDICTION Also called “substance use disorder” It  is a  neuropsychological  disorder characterized by a persistent and intense urge to use a  drug   or engage in a behavior that produces natural reward, despite substantial harm and other negative consequences. Procuring the drug and using it takes precedence over other activities. Repetitive drug use often alters  brain function and weakens self-control. Drug addiction increases the levels of dopamine ( control the brain’s reward and pleasure centers ) These increased levels of dopamine create feelings of pleasure and euphoria. Examples of drug addictions include  alcoholism ,  cannabis addiction ,  amphetamine addiction ,  cocaine addiction ,  nicotine addiction ,  opioid addiction , and etc. 

5. Effects Of Drug Addiction Changes in appetite, body temperature and sleeping patterns Wild mood swings, anxiety, paranoia, depression, and violence Heart rate irregularities, heart attack Hallucinations Confusions Kidney and liver damage Abdominal pain, vomiting, constipation, diarrhoea Seizures, stroke

6. TOLERANCE Drug tolerance  or  drug insensitivity  is defined as reduced response to a drug following its repeated use. Increasing its dosage may re-amplify the drug's effects; however, this may accelerate tolerance, further reducing the drug's effects . Drug tolerance is not necessarily associated with dependence and addiction. Mechanisms of tolerance Pharmacodynamic tolerance (cellular tolerance) Cellular response to a substance is reduced with repeated use. Due to high concentrations of a substance constantly binding with the  receptor , desensitizing it through constant interaction. Pharmacokinetic tolerance (drug disposition tolerance) Occurs because of a decreased quantity of the substance reaching the active site. Increase in  induction  of the enzymes required for degradation of the drug . Ex: ethanol

7. Types of tolerance Natural: The species/individual is inherently less sensitive to the drug, Ex: rabbits are tolerant to atropine; black races are tolerant to mydriatics. 2) Acquired: This occurs by repeated use of a drug in an individual who was initially responsive Ex: Tolerance develops to the sedative action of chlorpromazine but not to its antipsychotic action . Tolerance occurs to Analgesic & Euphoric action of Morphine , but not as much to its constipating & miotic actions . 3) Cross tolerance: It is the development of tolerance to pharmacologically related drugs, Ex: alcoholics are tolerant to barbiturates and general anesthetics. Closer the two drugs are, more complete is the cross tolerance between them. Ex: partial cross tolerance between morphine and barbiturates but complete cross tolerance between morphine and pethidine

8. TACHYPHYLAXIS (Tachy-fast, phylaxis-protection) It is a subcategory of drug tolerance It is an acute, sudden decrease in response to a drug after the repeated administration of a drug in quick succession . This change usually occurs very abruptly. Examples of tachyphylaxis 1 ) Nitrates for chest pain:  People taking   nitrates at frequent intervals  might not experience as much symptom relief. 2) Oxymetazoline : for reliving nasal congestion But taking it for more than a few days in a row can cause tachyphylaxis and a return of congestion .

9. IDIOSYNCRASY It is genetically determined abnormal reactivity to a chemical. The drug interacts with some unique feature of the individual, not found in majority of subjects, and produces the uncharacteristic reaction.

10. DRUG ALLERGY Drug Allergies  occur when your immune system reacts to a drug or a metabolite of drug, that usually doesn't cause a reaction in most people. It is an immunologically mediated reaction producing stereotype symptoms which are unrelated to the pharmacodynamic profile of the drug Generally occur even with much smaller doses of the drug. This is also called drug hypersensitivity . The target organs primarily affected in drug allergy are Skin Airways Blood vessels & Blood Gastrointestinal tract

11. The drug or its metabolite acts as antigen (AG) or hapten (incomplete antigen: drugs have small molecules which become antigenic only after binding with an endogenous protein) and induce production of antibody (AB)/sensitized lymphocytes

12. Mechanism and types of allergic reactions

13. Mechanism and types of allergic reactions A. Humoral Type-I (anaphylactic) reactions ( IgE ) are produced which get fixed to the mast cells. On exposure to the drug, AG: AB reaction takes place on the mast cell surface which causes mast cell degranulation Mediators released upon Degranulation = histamine, 5-HT, leukotrienes (especially LT-C4, D4), prostaglandins, PAF Symptoms: urticaria, itching, Angioedema, bronchospasm, rhinitis Anaphylactic shock

14. 2) Type-II (cytolytic) reactions e.g. Thrombocytopenia Agranulocytosis Aplastic anaemia Haemolysis Organ damage (liver, kidney, muscle)

15. 3) Type-III (retarded, Arthus ) reactions

16. B. Cell mediated 4) Type-IV (delayed hypersensitivity) reactions These are mediated through production of sensitized T lymphocytes carrying receptors for the AG. On contact with the AG these T cells produce lymphokines/cytokines which attract granulocytes and generate an inflammatory response e.g. Dermatitis Rashes Fever photosensitization

17. Treatment of drug allergy Antihistamines (H1) are beneficial in some type I reactions (urticaria, rhinitis, swelling of lips, etc.) In case of anaphylactic shock or angioedema of larynx administer oxygen at high flow rate Inject adrenaline 0.5 mg i.m. Administer H1 antihistaminic ( chlorpheniramine 10–20 mg) i.m. /slow i.v I.V glucocorticoid (hydrocortisone sod. succinate 200 mg)