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Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
Introduction to psychopharmacology
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Introduction to psychopharmacology

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Psych II

Psych II

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  • 1. INTRODUCTION TO PSYCHOPHARMACOLOGY
    HYACINTH C. MANOOD, MD, FPPA
  • 2. GENERAL PRINCIPLES:
    Classification
    Pharmacological Actions
    Pharmacodynamics
    Pharmacokinetics
    Metabolism and Excretion
    Clinical Guidelines
    Special Treatment Considerations
    Adverse Effects
    Discontinuation or Withdrawal Syndrome
    Intoxication or Overdose
  • 3. CLASSIFICATION
    Psychotropic, psychoactive, or psychotherapeutic drugs
    4 traditional categories:
    1)antipsychotics, 2)antimanic or mood stabilizers, 3)antidepressants,
    4)antianxiety or anxiolytics
  • 4. Many drugs of one class are used to treat disorders previously assigned to another class.
    Drugs from all four categories are used to treat disorders previously not treatable by drugs.
    Some non-psychiatric drugs can treat a variety of psychiatric disorders effectively but do not fit easily into the traditional classification.
    e.g., Clonidine, Gabapentin, Propanolol
    Some descriptive psychopharmacological terms overlap in meaning.
    eg. Anxiolytics also have sedative effects
  • 5. Pharmacological Actions
    Pharmacodynamics
    Effects of the drug on the biological activities of the body.
    Receptor mechanism
    Therapeutic index
    Dose response curve
    Development of tolerance, dependence, and withdrawal phenomena
  • 6. Receptor– the cellular component to which the drug binds and through which the drug initiates its pharmacological effects on the body.
    Dose Response Curve – plots the drug concentration against the effect of the drugs.
    POTENCY – the relative dose required to achieve certain effects.
    CLINICAL EFFICACY – the max clin. Response achievable by administration of a drug
  • 7. Therapeutic index - a relative measure of the toxicity or safety of a drug
    - ratio of the median toxic dose to median effective dose.
    median toxic dose – dose at which 50% of patients experience a specific toxic effects
    median effective dose – dose at which 50% of patients experience a specified therapeutic effect.
  • 8. Pharmacokinetics
    How the body handles the drug.
    Absorption :
    Orally administered drugs dissolve in GIT fluids and are then absorbed in the blood – then reach the brain.
    Parenteral administration more rapid than oral
    Depot preparations – emulsified in an insoluble carrier matrix sustaining the drug’s gradual release through IM administration
    IV administration is the quickest route but carries the highest risk of sudden and life-threatening adverse effects.
  • 9. Distribution and Bioavailability
    Protein-bound – bound to plasma proteins
    Free – if the circulate unbound
    Only the free fraction can pass thru the BBB
    High CBF, high lipid solubility, and high receptor affinity promote therapeutic actions of the drug
    Volume of distribution- measure of apparent space in the body available to contain the drug.
    Bioavailability - the fraction of the total amount of administered drug that can be subsequently recovered from the bloodstream.
  • 10. Metabolism and Excretion
    4 major metabolic routes:
    1.)oxidation 3.)hydrolysis
    2.)reduction 4.)conjugation
    - yields inactive metabolites that are more readily excreted
    - transform inactive prodrugs into therapeutically active metabolites.
    • The LIVER is the principal site of metabolism
    • 11. BILE, FECES, and URINE are major routes of excretion
  • Half-life - the amount of time it takes for metabolism and excretion to reduce a particular plasma concentration into half.
    First-pass effect – initial metabolism of orally-administered drugs within the portal circulation of the liver;
    Clearance – measure of the amount of drug excreted from the body in a specified period of time.
  • 12. CYTOCHROME P450 ENZYMES
    Most psychotropic medications are oxidized by hepatic CYP enzyme system.
    Act primarily in ER of hepatocytes and cells of the intestines.
    Cellular pathology in these sites may affect the efficiency of drug metabolism by the CYP system
    Certain drug combinations should be done so with caution or should be avoided.
    Long half-lives prolong inhibition of CYP system
  • 13. Clinical Guidelines:
    Choice of Drug
    Diagnosis and identification of target symptoms
    Drugs currently taken and recently discontinued
    Supotimal dosage of appropriate drugs
  • 14. Special Treatment Considerations
    A. GERIATRIC PATIENTS
    -older persons may be especially susceptible to adverse effects
    -slow metabolism
    B. CHILDREN
    - small volume of distribution
    - higher rate of metabolism
  • 15. C. PREGNANT AND NURSING WOMEN
    - the two most teratogenic drugs in psychopharmacology are LITHIUM and the ANTICONVULSANTS.
    Lithium – birth anomalies like Ebstein anomaly
    Anticonvulsants – fetal craniofacial and neural tube anomalies
    - Risk of teratogenicity is lowered by administration of FOLIC ACID
  • 16. D. PERSONS WITH HEPATIC AND RENAL INSUFFICIENCY:
    - drugs may accumulate to toxic concentrations.
    - reduced dosage, usually half the recommended dose.
    - monitor plasma drug concentrations
    E. PERSONS WITH OTHER MEDICAL ILLNESSES
    - increased sensitivity to adverse effects
    - altered metabolism
    - interactions with other medications
  • 17. Adverse Effects
    Sexual dysfunction – most commonly associated with the use of SSRI.
    Tx. Shift to Nefazodone or Bupoprion
    Anxiety, Akathisia, and Insomnia – SSRI and antipsychotics.
    Tx. Benzodiazepines, Anticholinergics, shift to non SSRI antidepressants
    GI upset and Diarrhea – Sertraline most likely to cause loose stools, Fluvoxamine most likely to cause nausea;
    Tx. Begin with low dose, adm drug after eating, BRAT diet.
  • 18. Headache – SSRI; Tx: ovr the counter analgesics
    Anorexia – SSRI
    Weight gain – atypical antipsychotics bec. of disturbance in glucose and insulin metabolism
    TX. Diet
    Somnolence – desirable adverse effect
    Dry Mouth – caused by blockade of muscarinic acetylcholine receptors
    Tx. Chew sugarless gum, 1% solution of Pilocarpine as mouthwash 3x a day
  • 19. Urinary Retention – anticholinergic activity
    Tx. Betanechol 10 -30 mg once or twice daily
    Constipation – Tx. Laxatives, Betanechol
    Orthostatic hypotension – caused blockade of a1-adrenergic receptors.
    TX. Instruct patient to get up slowly and sit down immediately if dizziness is experienced.
    Avoid caffeine
    Drink at least 2 Liters of fluids daily
    adding salt to food
    reassess dosages of antihypertensive meds
  • 20. Discontinuation Syndrome – transient emergence of mild symptoms upon the discontinuation or reduction of dosage
    SSRI . TCAC’s, Lithium, DRA, Benzodiazepines
    Lithium – rebound mania
    DRA – tardivedyskinesia
    Benzodiazepines – anxiety and insomnia
    SEROTONIN DISCONTINUATION SYNDROME
    Agitation, nausea, dysequilibrium and dysphoria
    Symptoms are time-limited
    Minimized by gradually reducing the dosage

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