PSYCHIATRIC MEDICATIONS ANTIPSYCHOTICS ANTIDEPRESSANTS Psychiatric Disorders Medical Model

PSYCHIATRIC MEDICATIONS ANTIPSYCHOTICS & ANTIDEPRESSANTS

Psychiatric Disorders Medical Model of Mental Illness Pros and Cons Assumes biological etiology Potentially treatable with psychotropic drugs There are no simple diagnostic tests for mental disorders. Diagnosis is based on assessment of behavioral symptoms.

Classification of Mental Disorders Anxiety Disorders Generalized Anxiety Disorder, Phobic Disorder, Panic Disorder, Obsessive Compulsive Disorder, Post-traumatic Stress Disorder Psychotic Disorders Schizophrenia, Schizoaffective Disorder Affective (Mood) Disorders Dysthymia, Major (Unipolar) Depression, Bipolar Disorder

Historical Developments in the Treatment of Mental Disorders Before 1950, “Malaria therapy” Thiopental sodium – truth serum Insulin shock therapy Electroconvulsive therapy Development of Phenothiazines in 1950 s

ANTIPSYCHOTIC DRUGS Historical Background “Accidental” discovery of promethazine and then chlorpromazine by Henri Laborit, 1951 Largactil marketed in Europe, 1953 Thorazine marketed in U. S. , 1955 Other Names for Antipsychotic Drugs Neuroleptic Literally means “clasping the neuron” Refers to parkinsonian-like side effects of these drugs “Major” Tranquilizers Refers to sedating effects Misleading terminology , chemically and pharmacologically distinct from “Minor” tranquilizers (the benzodiazepines and barbiturates)

Consequences of Psychiatric Medications for Society Dramatic decline in numbers of people institutionalized Increase in outpatient treatment programs Psychiatrists roles have changed From hospitals to jails or on the streets Number of patients in nonfederal hospitals, 1946 -2002 (Figure from Ksir et al. , 2007).

Classifying Antipsychotics Typical (Classical or Traditional) Phenothiazines or similar to phenothiazines e. g. , chlorpromazine, haloperidol Atypical , 2 nd generation e. g. , clozapine, risperidone, olanzapine, quetiapine, Atypical, 3 rd Generation e. g. , aripiprazole, amisulpride, ziprasidone

PHENOTHIAZINES: PHARMACOKINETICS Routes of Administration/Absorption Oral administration common, although absorption is erratic and unpredictable. In some cases (e. g. , poor compliance with oral meds), Depot injections (I. M. ) may be given, once a month. Distribution Rapid distribution throughout the body Easily cross blood brain barrier and placenta Considerable protein binding in blood Lower brain concentration compared to other body tissues Absorbed in body fat and released slowly Elimination Half-life: 24 -48 hours Slow elimination due to protein binding and accumulation in body fat Determining optimal dose, trial and error.

PHENOTHIAZINES: NEUROPHARMACOLOGY Neuropharmacological Mechanisms Block DA, NE, ACh, and histamine receptors CNS actions Limbic System: main therapeutic effects Brain Stem: suppress behavioral arousal, antiemetic effects Basal Ganglia: akathesia, dystonia, parkinsonism, and Tardive Dyskinesia Hypothalamus-Pituitary: temperature regulation impaired, breast enlargement, lactation, impotence, infertility

PHENOTHIAZINES: SIDE EFFECTS Side Effects/Toxicities Sedation due to antihistamine and antiadrenergic effects Postural hypotension due to antiadrenergic effects dry mouth, blurred vision, constipation, urinary retention tachycardia due to anticholinergic effects Extrapyramidal effects due to antidopaminergic effects in basal ganglia Impaired cognition due to anticholinergic effects Despite many side effects, antipsychotics are not lethal; high therapeutic index (100 to 1000) Tolerance/Dependence Tolerance develops to some of the side effects, but there is NO evidence of tolerance to therapeutic effects. These drugs do not produce physical dependence, perhaps due to extremely slow elimination from the body.

OLDER ALTERNATIVES TO PHENOTHIAZINES haloperidol (Haldol) Structurally distinct from phenothiazines Similar pharmacological mechanisms and similar side effect profile Effective for treating acute psychosis due to rapid onset, especially by injection molindone (Moban) Introduced in 1970 s, structurally similar to 5 -HT Similar therapeutic and side effects to traditional antipsychotics loxapine (Loxitane) Despite structural similarity to clozapine, effects more similar to traditional antipsychotics pimozide (Orap) In U. S. primarily used in tx. of tics in Tourette’s Syndrome Similar side effects to traditional neuroleptics, QT prolongation potentially severe

ATYPICAL ANTIPSYCHOTICS clozapine (Clozaril) Background Synthesized in 1959 and introduced into clinical practice in Europe in early 1970 s Fatalities due to agranulocytosis delayed introduction in the U. S. 1986, clinical trials in U. S. Pharmacokinetics p. o. , absorbed well, peak plasma levels in 1 -4 hours variable half-life 9 -30 hours Blood monitoring especially important

ATYPICAL ANTIPSYCHOTICS clozapine continued Pharmacodynamics High binding affinity for D 4, 5 -HT 1 C, 5 -HT 2, NEa 1, muscarinic and histamine receptors Low D 2 affinity Side Effects/Toxicity Sedation in about 40% of patients Weight gain for up to 80% of patients Constipation in about 30% of patients Agranulocytosis rare Withdrawal symptoms may occur upon discontinuation, alleviated by olanzapine

ATYPICAL ANTIPSYCHOTICS risperidone (Risperdal) Introduced in 1993 Pharmacokinetics p. o. , well absorbed Highly bound to plasma proteins Half-life about 3 hours, active metabolite with 22 hr. halflife Pharmacodynamics Less effective than clozapine in relieving positive symptoms, equally effective in relieving negative symptoms Better safety profile than clozapine Side Effects Somnolence, agitation, anxiety, headache, nausea EPS at high doses (> 8 mg/day) Weight gain less than with clozapine or olanzapine

ATYPICAL ANTIPSYCHOTICS olanzapine (Zyprexa) Introduced in 1996 structurally/pharmacologically similar to clozapine, no agranulocytosis Pharmacokinetics p. o. , well absorbed, peak plasma levels 5 -8 hours Half-life 27 -38 hours Pharmacodynamics Superior or comparable to haloperidol Comparable efficacy to clozapine Side Effects Weight gain no agranulocytosis occasional EPS Other Uses of Olanzapine Bipolar disorder Pervasive Developmental Disorder Agitation and Aggression

ATYPICAL ANTIPSYCHOTICS Other Atypicals sertindole (Serlect) 1997 D 2/5 -HT 2 antagonist, no antihistaminic effects Prolonged QT interval, removed from market quetiapine (Seroquel) 1998 D 2/5 -HT 2 antagonist, similar to clozapine Side effects: nausea, sedation, dizziness, weight gain no different from placebo Other uses: bipolar, OCD ziprasidone (Geodon) D 2/5 -HT 2 antagonist, 5 -HT 1 A agonist Relieves positive and negative symptoms, no weight gain First atypical approved for IM use Antidepressant activity, also effective in Bipolar disorder Cardiac effects are a limiting factor, prolongs QT interval

“Third Generation” Antipsychotics Aripiprazole Pharmacodynamics Considered a DA-5 -HT system stabilizer 5 -HT 2 antagonist, partial D 2 and 5 -HT 1 A agonist No serious side effects Other recent uses Bipolar disorder, conduct disorder in children Amisulpride D 2/D 3 antagonist in limbic areas, not b. g. Low doses inc. DA release, high doses block First atypical that doesn’t block 5 -HT receptors

ATYPICAL ANTIPSYCHOTICS Potential Health Risks of Atypical Antipsychotics Weight Gain hinders patient compliance Diabetes/Hyperglycemia Electrocardiographic Abnormalities

Behavioral Effects of Antipsychotics Subjective Effects In healthy subjects, classical neuroleptics produce slow and confused thinking, difficulty concentrating, clumsiness, sedation, some anxiety and irritability. These effects probably responsible for poor compliance among patients prescribed these drugs. Atypical antipsychotics less of a problem. Performance Few studies and reports are variable (deficits, improvements, no effect) Studies of acute effects on cognitive performance indicate impairments are due to sedation and tolerance to these effects occur within 14 days.

Laboratory Studies in Nonhumans Unconditioned Behavior Suppression of spontaneous movement with high doses causing immobility (which gave rise to the name neuroleptic) Diminish frequency and intensity of aggressive behavior in most species, possibly due to decreased motor function. Conditioned Behavior Decrease responding on schedules maintained by positive reinforcement, although low doses may increase low response rates (rate dependency similar to amphetamine) Decrease avoidance responding without affecting escape behavior, similar to CNS depressants.

Laboratory Studies in Nonhumans Drug Discrimination Some antipsychotics not easily discriminated, large doses and extended training required. Generalization does not occur between Atypicals (e. g. , clozapine) and Typicals (chlorpromazine) or between antipsychotics and other drug classes. Self-administration Antipsychotics are NOT self-administered by nonhumans. They are never abused by humans. In fact, compliance among patients is often a problem.

ANTIDEPRESSANTS & MOOD STABILIZERS

DEPRESSION Symptoms extreme sadness/despair, diminished interest in pleasure, diminished energy, loss of appetite/weight loss, mental slowness, concentration difficulties, restless agitation, insomnia, recurrent suicidal thoughts DSM-IV criteria list nine categories of symptoms with five or more symptoms present during same two week period Prevalence in U. S. Approx 50% 14 million (6. 6 % of adults) receive medical treatment, which is effective in only about 42% of those treated

Depression Pathophysiology of Depression A “reversible brain disease” Structural, neurochemical changes in hippocampus, frontal cortex Once thought to be a consequence of neurotransmitter deficiencies (e. g. , NE, 5 -HT) More recent evidence suggests reductions in neurotrophic hormones and reduced neuronal plasticity are key factors in pathophysiology of depression.

Classifying Antidepressants First Generation (introduced in 1950 s-1960 s) MAO Inhibitors Tricyclics Second Generation, Atypical (1970 s-1980 s) SSRIs (~ 1990 s) SNRIs Dual-Action Antidepressants Combined SSRI + 5 -HT 2 antagonist or combined SSRI/SNRI

MAO Inhibitors Examples of MAOIs Iproniazid: first one introduced in 1950 s, no longer on the market phenelzine (Nardil) tranylcypromine (Parnate) moclobemide (Ludiomil): not available in U. S. Pharmacokinetics Short half-life, 2 -4 hours Neuropharmacological Actions Block degradation of monoamines by MAO Indirect Agonist for all Monoamines

MAO Inhibitors Side Effects potentially fatal interactions with foods containing tyramine or with adrenergic drugs; hypertensive crisis. MAO-A vs. MAO-B Both in CNS: MAO-A mainly acts on NE and 5 -HT; MAO-B mainly acts on DA. MAO-A, in gastrointestinal tract; MAO-B, in liver and lungs Older MAOIs acted on both types, side effects such as hypertensive crisis with tyramine rich foods. Recent advances Selective MAO-A inhibitor, moclobemide (not available in U. S. ) Transdermal delivery of selegiline (Eldapril)

Tricyclic Antidepressants Examples imipramine (Tofranil) amitriptyline (Elavil) desipramine (Norpramin) Pharmacokinetics well absorbed with oral administration long half-lives, ~ 24 hours metabolized in liver

Tricyclic Antidepressants Neuropharmacological Effects monoamine reuptake blockade Indirect agonist for all monoamines Side Effects Antihistaminergic effects: sedation Anticholinergic effects: dry mouth, blurred vision, urinary retention, increased heart rate, cognitive impairments overdose can be fatal due to cardiac toxicity, concern with suicidal patients

SSRIs & SNRIs SSRIs fluoxetine (Prozac) Sertraline (Zoloft) paroxetine (Paxil) Fluvoxamine (Luvox) citalopram (Celexa) SNRIs atomoxetine (Straterra) Commercially available in 2003 for ADHD treatment reboxetine (Edronax, Vestra) Not currently available in U. S.

Dual Action Antidepressants nefazodone (Serzone) 5 -HT 2 receptor antagonist and 5 -HT/NE reuptake blocker; chronic use down regulates NE/5 -HT receptors. mirtazepine (Remeron) Tetracyclic and Na. SSA 5 -HT 2/5 -HT 3 receptor antagonist; also antihistamine duloxetine (Cymbalta) 5 -HT/NE reuptake blocker also prescribed for chronic pain conditions, such as diabetic neuropathy and fibromyalgia venlafaxine (Effexor) 5 -HT/NE reuptake blocker also prescribed for general anxiety disorder

Behavioral Effects of Antidepressants Subjective Effects These drugs do not produce euphoric or pleasant effects and may produce fatigue, apathy, weakness. High doses may impair comprehension, cause confusion and reduce concentration. Performance Acute doses have detrimental effects on vigilance tasks and can cause memory and psychomotor impairments related to sedation. With repeated use, these effects show tolerance.

Laboratory Studies in Nonhumans Unconditioned Behavior Antidepressants tend to increase locomotor activity in rodents Conditioned Behavior Increase response rates in operant assays, both low and high rates Decrease avoidance responding without affecting escape behavior, similar to anxiolytic and antipsychotic drugs. Do not increase, but tend to decrease punished responding.

Laboratory Studies in Nonhumans Drug Discrimination MAOIs and tricyclics are not discriminated, except at extremely high doses SSRIS and SNRIs are discriminated at therapeutic doses. Self-Administration None of the antidepressants are self-administered by nonhumans.

Health Risks of Antidepressants Reproduction Males, delayed or impaired ejaculation Males and females, Reduced sex drive and difficulties achieving orgasm. Teratogenic effects with some antidepressants e. g. , increased risk of miscarriage with fluoxetine and TCAs. e. g. , Lithium in early pregnancy can cause cardiac malformations in fetus. Violence/Suicide Evidence for this largely from case studies. Large scale studies actually show reduced incidence of suicide and violence.

Health Risks of Antidepressants Overdose SSRIs at high doses or combined with other antidepressants or stimulants can cause Serotonin Syndrome (excess serotonin transmission) Disorientation, agitation, fever, chills, diarrhea If untreated, can lead to respiratory, circulatory, and kidney failure. TCAS third most common cause of drug-related fatalities Therapeutic index of TCAs only ~10 -15. SSRIs considerably safer in this regard.

Bipolar Disorder Characteristic Symptoms recurrent episodes of mania and depression widespread cognitive deficits subtypes of varying severity (I, II, cyclothymia) Prevalence up to 5% of population

Bipolar Disorder Treatment Issues long-term management is key Ideal treatment is to: stabilize acute symptoms not induce alternate mood symptoms prevent future relapses

Bipolar Disorder Neuropathology of BD Initially conceptualized as a neurochemical imbalance Recent evidence of neuronal injury Regional differences in neuronal density Evidence of neuronal pathology in hippocampus Cause or Effect? Mechanisms of Drug Action Recent evidence indicates antimanic drugs (e. g. , lithium, valproic acid) increase levels of cellularprotective proteins and appear to reduce brain damage.

Lithium History 1940 s, Lithium Chloride was used as salt substitute severe toxicity, deaths 1949, John Cade’s studies in Guinea Pigs acceptance by medical community delayed Lithium Carbonate 1970 s, clinical research demonstrated clear evidence for superior efficacy Today’s “gold standard” in treating Bipolar Disorder. Problems with compliance, largely due to side effects

Lithium Pharmacokinetics Absorption Rapid by p. o. route Peak blood levels within 3 hours, complete absorption within 8 hours Therapeutic efficacy directly correlated to blood levels Crosses BBB slowly and incompletely Elimination excreted unchanged by kidneys 18 -24 hr. half-life When initiating once daily dosing, blood levels accumulate slowly over 2 weeks until steady levels reached. Determining Therapeutic Dose Close blood level monitoring required Recommended levels ~ 0. 5 -0. 7 m. Eq/l Salt intake/excretion should be constant to avoid adverse effects of Lithium

Lithium Pharmacodynamics Lithium produces specific actions on mania, with no psychotropic effects in normal individuals. Mechanism of action not well understood second messenger signaling pathways e. g. , modulation of intracellular protein kinase enzymes elevation of cellular protective protein, bcl-2

Lithium Side Effects and Toxicities Multiple Organ Systems GI: nausea, vomiting, diarrhea, abdominal pain Kidneys: increased urine output, increased thirst and water intake Thyroid: depressed function, becomes enlarged, weight gain Skin: rashes CNS: tremor, lethargy, impaired concentration and memory, dizziness, slurred speech, ataxia, muscle weakness, nystagmus Cardiovascular: cardiac arrhythmia

Lithium Effects in Pregnancy Teratogenic potential, particularly heart Generally not advised during pregnancy, especially during first trimester. If necessary tx. in a pregnant woman, discontinue use several days before delivery. Problems with Compliance Up to 50% of patients stop using AMA. recurrent manic episodes and greatly increased suicide risk Noncompliance largely due to intolerance of side effects, in particular weight gain and cognitive effects.

Neuromodulators/Anticonvulsants Carbamazepine (Tegretol) Studies in early 1990 s indicated efficacy equivalent to lithium, although more recent studies show lithium to be superior. Some patients resistant to both drugs respond to combination of the two. Adverse effects include GI upset, sedation, ataxia, impaired vision, skin reactions, modest cognitive effects. More serious risk: low white blood cell count, requires blood monitoring Drug interactions due to stimulation of CYP 3 A 4 liver enzymes Teratogenic: neural tube defects in 1%

Neuromodulators/Anticonvulsants Valproic Acid (Depakote) Introduced in 1994 GABA agonist specific mechanisms of antimanic actions not yet determined some evidence that gene expression modulated Particularly effective in tx of acute mania, schizoaffective disorder, rapid cycling bd Positive response in 71% of lithium-resistant pts. Increased efficacy in combination with Lithium compared to either drug alone. Side effects: GI upset, sedation, lethargy, tremor, hair loss, cognitive impairments (in females, weight gain, polycystic ovaries, increased androgens) Potential toxicities: liver, pancreas, also teratogenic

Neuromodulators/Anticonvulsants Gabapentin (Neurontin) Introduced in U. S. as anticonvulsant in 1993 Similar clinical efficacy to valproic acid, except gabapentin superior analgesic, valproate superior in tx of BD GABA analogue, increases GABA levels in brain Excellent pharmacokinetic profile: no binding to plasma proteins, not metabolized, excreted unchanged by kidneys, few pk drug interactions, half-life 5 -7 hours Results of clinical studies suggest this agent is most effective as adjunctive med. In pts. resistant to other more effective mood stabilizers. Side effects: dizziness, dry mouth, somnolence, nausea, flatulence, reduced libido

Neuromodulators/Anticonvulsants Other Neuromodulators Pregabalin Lamotrigine antiepileptic, alcohol relapse prevention; key advantage weight loss Tiagabine Improvement on carbamazepine Topiramate effective tx of acute bipolar depression, poor tx of acute manic episodes Inhibits glutamate release Skin rashes possible serious side effect Oxcarbazine under development for tx of GAD limited efficacy, no controlled studies in tx of BD Zonisamide Mid-2000 became available in U. S. , prelim. studies show promise

Atypical Antipsychotics for Bipolar Disorder Olanzapine (Zyprexa) Recent studies have shown equivalent efficacy to lithium or valproic acid mid-2000 FDA approved for short-term treatment of acute mania Quetiapine (Seroquel) Recent studies show efficacy in treatment of Bipolar Disorder Others to be investigated ziprasidone aripiprazole