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Pharmacology Section 10. Antidepressants and mood stabilizing drugs Marta Jóźwiak-Bębenista [email protected] Affective disorders psychiatric diseases 1. Major depressive disorder (MDD) monopolar depression/ unipolar affective disorder Dysthymic disorder Seasonal affective disorder (SAD) Postpartum depression („baby blues”) Premenstrual dysphoric disorder (PMDD) Substance-iduced mood disorder 2. Bipolar affective disorder (BAD) manic depressive disorder alternating manic, normal and depressive episodes Depression everyone feels "blue" at certain times transitory feelings of sadness are perfectly normal clinical depression is a serious condition that affects a person's mind and body. all aspects of everyday life including eating, sleeping, working, relationships, and how a person thinks about himself/herself. cannot simply will themselves to feel better or „snap out of it” symptoms can continue for weeks, months, or years at untreated patients Statistics and Information about depression Depression affects almost 10% of the population, or 19 million Americans, in a given year During their lifetime, 10%-25% of women and 5%-12% of men will become clinically depressed Women are affected by depression almost twice as often as men - hormonal changes brought on by puberty, menstruation, menopause, and pregnancy. - suicide is serious risk for men with depression, 4 times more likely than women It can affect any person at any age (usually 25-44) Statistics and Information about depression Two-thirds of those who are depressed never seek treatment and suffer needlessly - personal weakness or character flaw do not recognize the signs or symptoms that something may be wrong. 80%-90% of those who seek treatment for depression can feel better within just a few weeks - one-third of those who are depressed actually receive treatment Depression as the "common cold" of mental illness. The economic cost of depression is estimated to be over $30 billion each year Symptoms of depression Emotional usually worst in the morning – – – – – – depressed mood most of the day, nearly every day sad, anxiety or “empty” feelings lack of pleasure in usual activities no interest in the future. restlessness, irritability, pessimism feelings of guilt, worthlessness, helplessness, and hopelessness – difficulty thinking, such as concentrating or making decisions, memory impairment - recurrent thoughts of death or suicide Symptoms of depression Physical (biological) – change in sleep patterns. usually early morning awakening inability to sleep sleeping too much – change in appetite and weight decreased appetite with weight loss (most common) sometimes increased appetite with weight gain – loss of energy or fatigue – unexplained physical problems: headaches, stomach problems, aches and pains,… People who are depressed may not experience all of these symptoms. Some will have many symptoms, others will have just a few. In order to make diagnosis of a major depressive disorder, the symptoms (five or more) must have been present without a return to normality for at least 2 weeks. Causes of depression It is not fully known what exactly causes clinical depression. Numerous theories: biological causes genetic causes environmental influences Clinical depression is most often caused by the influence of more than just one or two factors. Biological causes of depression 1. monoamine theory The drugs, that will be increasing neurotransmission, in aminergic neuron systems will be used in depression treatment. 2. Cortisol- hormone that the body produces in response to stress Depressed patients have a raised baseline cortisol concentration Deficit of monoamines: NA, 5-HT, DA in the brain Concentration in the synaptic cleft Neurotransmission in the brain Biological causes of depression inadequate neurotransmitter signalling – functional deficit of NA, DA and 5-HT (monoamine theory) – desensitization of β-adrenergic and 5-HT2A receptors – dopaminergic system – GABA – peptidergic systems (AVP, opiates) Reducing the central serotonin, noradrenaline, and dopamine concentration can lead to depression Drugs that increase the central serotonin, noradrenaline, and dopamine concentration improve depression! Causes of depression genetic causes - the result of what patients inherit from parents - If one or both parents have a vulnerability to depression, then it can be transmitted to their children. - if one identical twin suffers from depression or manic-depressive disorder, the other twin has a 70% chance environmental influences - stress, breakup of important attachments (lack of loving parents, death of a parent during childhood), physical illness (medication, substance abuse) Treating depression 1. 2. Antidepressant drugs Electroconvulsive therapy (ECT) - success rate of 78% - ECT for individuals whose depression is severe or life threatening or is effective in cases where antidepressant medications do not provide sufficient relief of symptoms 3. - Psychotherapy learning about their disorder, learning to identify and avoid situations that may induce another depressive episode, view themselves and their situations more realistically, and to improve their interpersonal relationship skills. Herbal remedies St. Johns Wort Derived from Hypericum perforatum Most popular remedy in the world Appears effective for milder depression Side effects: phototoxicity available without prescription 900-1800mg/day is recommended dose Antidepressants Antidepressants Tricyclic antidepressants TCAs Selective serotonin reuptake inhibitors SSRIs Monoamine oxidase inhibitors MAOIs Mood stabilizer/ other drugs Antidepressants Antidepressants Tricyclic antidepressants TCAs Selective serotonin reuptake inhibitors SSRIs Monoamine oxidase inhibitors MAOIs Mood stabilizer/ other drugs Tricyclic antidepressants Since the 1950s Imipramine (Tofranil) Three-ring chemical structures Less popular choice than the new generation of antidepressants Similar therapeutic efficacy Choice of drug (side effects/duration of action) Change of medicine after three weeks Mode of action: beefing up the brain`s supply of NA, 5-HT levels Ø monoamine (NA, 5-HT) reuptake into presynaptic nerve from the synaptic cleft concentration of NE, 5-HT neurotransmission The antidepressant effect of TCAs occur after two weeks or longer of continued treatment !!! - decreased reuptake immediate effect not the antidepressant effect - long- term adaptational changes in receptors the antidepressant effect !!! - reuptake blocking potency doesn’t correspond with clinical potency Ø receptors for ACh, HA, 5-HT, α The important drugs of TCAs Tricyclic Antidepressants (TCAs) amitriptyline (Elavil, Endep) clomipramine (Anafranil) desipramine (Norpramin, Pertofrane) doxepin (Adapin, Sinequan) imipramine (Imavate, Janimine, Presamine, Tofranil) nortriptyline (Aventyl, Pamelor) protriptyline (Vivactil) trimipramine (Surmontil) Heterocyclic Antidepressants Second-generation • amoxapine (Ascendin) • maprotiline (Ludiomil) Pharmacokinetics 1. Absorption and distribution good absorption from GI tract upon oral administration lipophilic properties good BBB penetration long half-life (for imipramine 4-18 h) first-pass effect inconsistent and low bioavailability – patient’s response dose adjustment Pharmacokinetics 2. Fate TCAs are metabolized by enzymes Cyt.P450 metabolites pharmacologically active! Amitriptyline nortriptyline* Imipramine desipramine* Active metabolites prolong pharmacological effects excretion urine Therapeutic uses of TCAs severe depression - also prevents recurrence depression with anxiety panic and phobic disorders bet-wetting in children (imipramine) chronic or psychogenic pain bipolar disorder Side effects of TCAs 1. antimuscarinic effects: dry mouth, blurred vision, urinary retention, constipation and aggravation of glaucoma and epilepsy 2. postural (orthostatic) hypotension reflex tachycardia 3. 4. 5. 6. cardiovascular (heart failure, hypertension, hypotension, sudden death, arrhythmias, ECG changes) sedation hormonal effects (loss of libido, impotence) others: gastric irritation, weight change, allergic skin reactions and jaudince Contraindications to TCAs prostate narrow angle glaucoma recent myocardial infarction heart block, heart failure arrhythmias epilepsy Drug interaction of TCAs MAOI „serotonin syndrome” - life threatening! tachycardia, hypertension, hyperactivity, hyperpyretic crisis, convulsions, coma TCAs should not be given in conjunction with- or within at least two weeks of treatment with -a MAOI. TCA+MAOI= monitoring! Drugs having anticholinergic actions Central nervous system depressant (alcohol, barbiturates) Hepatic enzyme inhibitors (cimetidine, SSRI) Hepatic enzyme inducers (carbamazepine) Oral coumarin anticoagulants (increase effect) Guanetydyna (decrease effect) Tolerance and withdrawal with TCA’s Tolerance generally develops to anticholinergic and sedative side effects within a short time An occasional withdrawal syndrome is reported with abrupt discontinuation from high dosages. True dependence, however, does not occur TCAs can be used for prolonged treatment without loss of effectiveness Tricyclic antidepressants (!) unmask manic behavior in BAD (!) low TI suicidal attempts acute toxicity (arrhytmias, respiratory depression, convulsions,…) monitored closely Antidepressants Antidepressants Tricyclic antidepressants TCAs Selective serotonin reuptake inhibitors SSRIs Monoamine oxidase inhibitors MAOIs Mood stabilizer/ other drugs Selective serotonin-reuptake inhibitors SSRIs Introduced in the 1980s as a new antidepressants Replaced the TCAs Affect the serotonin-containing nerves safe, better tolerability, less severe side effects Less toxic in overdose than TCAs Do not require blood monitoring Mode of action of SSRIs Specifically inhibit 5-HT reuptake from synaptic cleft into presynaptic nerve terminals concentration of 5-HT in the synaptic cleft long term adaptational changes serotonin neurotransmission no effect on NE reuptake don`t have affinity for M, HA, 5-HT and α receptors SSRIs include: - Citalopram (brand name: Celexa), - Fluoxetine (brand name: Prozac), - Paroxetine (brand name: Paxil) - Sertraline (brand name: Zoloft) - Fluvoxamine Fluoxetine is now the most widely prescribed antidepressant in the United States! Pharmacokinetics of SSRIs 1. Absorption and distribution oral administration rapidly absorbed and distributed Active metabolites! – citalopram, fluoexetine, sertraline fluoexetine norfluoxetine* Norfluoxetine is 3x more selective, potent than parent drug fluvoxamine(+) no active metabolite t0.5 ~ 15 h fluoexetine t0.5 up to 30 days The long half-life of fluoxetine and its metabolite imposes cautious management when treatment is to be changed, because the drug lingers in the blood for some time after the treatment has been discontinued, this way increasing the risk of drug interactions. Side effects of SSRIs SSRIs have fewer side effects than TCAs (fewer anticholinergic effects and lower cardiotoxicity) • gastrointenstinal disturbances: nausea, vomiting, diarrhoea • headache, insomnia, • anxiety, agitation • sexual dysfunction (loss of libido, impotence) • allergic skin reactions • weight loss • tremors, seizures • serotonin syndrome! Therapeutic uses of SSRIs: Clinical Efficacy similar to that advantages: of TCAs - no anticholinergic Major depression effects - no orthostatic acceptability hypotension - no weight gain - no toxic in overdose - lower cardiotoxicity Therapeutic uses of SSRIs: 1. depression in early stages 2. minor depressive illness 3. anxiety disorders: - panic attacks - obsessive-compulsive disorder 2. eating disorders (bulimia nervosa, anorexia nervosa) 3. chronic pain (e.g. pain associated with diabetic neuropathy) 4. menstrual syndrome Drug interactions of SSRIs - MAOI „serotonin syndrome” It should wait at least two weeks between stopping MAOIs and starting an SSRI, or at least five weeks after stopping an SSRI and starting an MAOI. - TCAs monitoring! - tryptophan (headache, nausea, sweating and dizziness) - warfarin (excess bleeding) Drug interactions of SSRIs SSRIs are inhibitors of hepatic cytochrome P450 isoenzyme! metabolizes: - neuroleptics, - TCAs, - some antiarrhythmics - beta blockers paroxetine> fluoxetine> sertraline> citalopram>fluvoxamine - Hepatic enzyme inhibitors (cimetidine, SSRI) Hepatic enzyme inducers (carbamazepine) Antidepressants Antidepressants Tricyclic antidepressants TCAs Selective serotonin reuptake Inhibitors SSRIs Monoamine oxidase inhibitors MAOIs Mood stabilizers/ Other drugs MAOIs Adverse reactions associated with MAOIs are generally more frequent and severe than with other antidepressants. - reducing the dosage - monitoring the patients Use of MAO inhibitors is now limited, because of the complicated dietary restrictions required of patients taking MAOIs! Mechanism of action of MAOIs Inhibit the action of monoamine oxidase- MAO MAO-A 5-HT, NA Tyramine MAO-B Dopamine, phenylethylamine 1. irreversibly or reversible inactivation MAO 2. nonselective or selective - MAOI-A and MAOI-B selective + reversible: moclobemide less ADEs, INTs Mechanism of action of MAOIs Inactivation of monoamine oxidase – concentration of NA, 5-HT, DA in the presynaptic neuron – leakage of monoamines into synaptic space – monoamine transmission MAOIs: 1. Non-reversible/non-selective monoamine oxidase inhibitors (MAOIs) phenelzine - the hydrazine derivative, amphetamine-like activity. isocarboxazid - the hydrazine derivative tranylcypromine - non-hydrazine derivatives, amphetamine-like activity. 2. Non-reversible/ selective monoamine oxidase inhibitors Selegilina MAO-B 3. Reversible/ selective monoamine oxidase inhibitors Moclobemid Actions and Pharmacokinetics of MAOIs Actions: antidepressant action after 2-4 weeks amphetamine-like stimulatory Pharmacokinetics: oral administration long duration after discontinuation of treatment (~ 2 weeks) irreversibly inactivated Washout period The irreversibility of the binding of the enzyme by IMAO is a serious problem Effects of MAOIs continue until enough new, unbound MAO is synthesized ! Enzyme regeneration occurs several weeks after the ending of treatment wash-out period of at least 2 weeks should be allowed between stopping a MAOI and starting a TCA or a SSRI During this 2 weeks the patients should continue dietary and other restrictions until this time has elapsed. Therapeutic uses of MAOIs atypical depression (e.g appetite disorders) depression – if unresponsive to TCAs – if associated with strong anxiety – if associated low psychomotor activity resistant depression facial pain phobic states Adverse effects/interactions of MAOIs tyramine rich food (cheese, red wine, beer, chicken liver) „cheese reaction” – tyramine not inactivated by MAO catecholamine release tachycardia, headache, nausea, hypertension, cardiac arrhytmias, stroke – develops within 30 minutes to 1 hour after ingestion of the food – antidote phentolamine, prazosin Sympathomimetic agents (dopamine, ephedrine), opioid analgesics, narcotics TCAs or SSRIs „serotonin syndrome” – washout period of ~ 2 weeks when therapy change MAO blockade has the potential of serious and indeed lifethreatening consequences if the subject is exposed to certain agents, which would normally be metabolized by this same enzyme. The patients treatment MAOI must therefore be educated to avoid tyramine containing foods and some drugs. For these reasons, the MAOIs are no longer considered as first-choice antidepressants and are usually only prescribed after other options have failed. Foodstuffs (high in tyramine) to avoid with MAOIs Drugs to avoid with MAOIs: 1. sympathomimetic agents, such as: -dopamine -ephedrine -levodopa -pseudoephedrine 2. opioid analgesics 3. amphetamine 4. dextromethorphan 5. CNS depressant (e.g alcohol, narcotics) 6. SSRIs, TCAs Other side-effects a. b. c. d. e. f. Sleep disturbances, drowsiness Orthostatic hypotension Weight gain Sexual dysfunction Insomnia Peripheral neuropathy (pyridoxine deficiency) Contraindications to MAOIs: pheochromocytoma congestive heart failure liver disease Antidepressants Antidepressants Tricyclic ADs Selective serotonin reuptake inhibitors Monoamine oxidase inhibitors Other drugs Other drugs Heterocyclic Antidepressants The new generation drugs • • • • Second-generation bupropion (Wellbutrin) trazodone (Desyrel) amoxapine (Ascendin) maprotiline (Ludiomil) Third-generation • mirtazapine (Remeron) • venlafaxine (Effexor, Efectin) • nefazodone (Serzone) Second generation antidepressants Trazodone - SSRI, Ø NA and 5-HT receptors - may be used in schizophrenic patients Maprotiline - selective noradrenaline reuptake inhibitor (NARI) Bupropion (Wellbutrin) - selective dopamine reuptake inhibior, antinicotine treatment Third-generation antidepressants Venlafaxine – Serotonin-noepinephrine reuptake inhibitors (SNRIs) – clinical profile like SSRIs, quick onset of action Mirtazapine - noradrenergic and specific serotonergic antidepressant (NaSSA) - Ø presynaptic NA and 5-HT receptors Nefazodon ~ trazodon, less sedating Other atypical antidepressants: Mianserine –presynaptic α2 blocker –A: sedative, anxiolytic Tianeptine – 5-HT reuptake (???) –(+) few ADEs –ADE: hepatitis (rare) Viloxazine – NE reuptake –(+) not cardiotoxic or cholinolytic Drug choice The right drug and the right dose for the individual patient must be accomplished empirically and depends on: - the clinical characteristics of the patient`s illness - the drug`s adverse effect profile - toxicity in overdosage and dosing schedules - the past history of the patient`s drug experience The greater tolerability of the SSRIs and SNRIs, NaSSAs make them the preferred agents for most patients If there are no medical contraindications or no risk of suicide, a TCA can be used Drug choice MAOI – atypical depression One third of patients do not respond to any single treatment unresponsive patients SSRI+TCA (desipramine) / Bupropion / Mirtazapine lithium+SSRI A generally accepted strategy is to begin treatment with an SSRI in mild to moderate outpatient depression and then augment by adding a drug of a different class for more impaired patients Bipolar disorders also known as manic depression or manic-depressive illness Bipolar disorders Moods shift between two extremes For a period of time the person experiences the symptoms of depression (the depressive phase), then his mood will shift into a period of mania (euphoria) between these extremes a period of normal functioning the manic phase can be enjoyable distressing, disruptive to people`s life Manic Mania is caused by an overproduction of neurotransmitters in the brain. - lots of energy - extremely active and talkative - extremely happy or sometimes extremly angry - restless and irritable - racing thoughts - delusions - unable to sleep much - voices or see things that aren`t there – hallucinations - unrealistic beliefs in one's abilities and powers - abuse of drugs, particularly cocaine, alcohol, sleeping medications - a lasting period of behavior that is different from usual A manic episode is diagnosed if elevated mood occurs with three or more of the symptoms most of the day, nearly every day, for 1week or longer. Bipolar disorder as a spectrum or continuous range A mild to moderate level of mania is called hypomania. The patient shows signs of mania but doesn`t have delusions or hallucinations. In a hypomanic state, the patient may be able to continue with his life as normal. A depressive episode is diagnosed, if five or more of the symptoms of depression occur most of the day, nearly every day, for a period of 2 weeks or longer. So the depressive episodes in BPAD are clinically identical to depression in the absence of previous manic episodes. Bipolar disorder 2-3 million people suffer from bipolar depression (1-2% of the population) genetic factor (15% of children with one bipolar parent) begins during adolescence or early adulthood alcohol and drug abuse or anxiety disorders better controlled if treatment is continous than if is on and off! What It's Like Living With Bipolar Disorder? Joseph is feeling on top of the world. He has just come off a period where it was so difficult for him to do anything that he wanted to do. In fact, for a few months, he didn’t do anything. He just stayed in the house, most of the time sleeping. It is certainly different now. In fact, Joseph is almost always out of the house. He only needs two to three hours sleep a night and he feels that he has the energy of a bull. Joseph is spending most of his time on a new project. He is working on a new business venture that he knows is going to make him a fortune. Somewhere in the back of his mind he remembers that he has tried to start new businesses on numerous occasions and they have always resulted in financial disaster. However, those failures are in the back of Joseph’s mind now because he knows that this idea is a sure winner. He is spending most of his days trying to convince banks to lend him the money. He cannot understand why the banks that he has visited so far seem so negative, but Joseph is sure that he will find a bank soon that will advance him the large sum of money that he needs. He has spared no expense in this effort. Joseph has gone to the best stores and purchased a new wardrobe. He has ordered the latest in computer equipment. He also has hired a commercial realtor to find him modern offices. Joseph has not told his family about his new idea because they always rain on his parade. They are negative about all of his ideas. But he knows that they do not have the vision that he has and that they will eat their words when they see the millions that he is going to make with his new venture. Treatment of bipolar disorders medication – mood stabilizers supportive psychotherapy occasionally ECT Mood stabilizers are the usual treatment for bipolar illness. They prevent extreme mood swings. These drugs must be taken long term even when the patients feel well. Mood stabilizers 1. Lithium- this is the most common treatment and it works for about 60% of people. 2. Anticonvulsants drugs (such as Carbamazepine(Tegretol), valproate (Depakote), gabapentin (Neurontin) and lamotrigine Lamictal), these are given when lithium doesn`t work or when lithium is unsuitable Other: 3. antidepressants (such as bupropion (Wellbutrin)or sertraline (Zoloft)), 4. neuroleptics (e.g. haloperidol) 5. benzodiazepines (e.g. lorazepam) BPAD is treated with a combination of mood stabilizers, antipsychotics and antidepressants Lithium Mode of actions – unknown, proposed: mediated via effects on the IP3 and DAG secondmessenger systems Efficacious: - acute mania - prophylaxis of classical bipolar disorder - mania/hypomania-depression the onset of action (7-10 days) excreted by the kidney the high frequency of non-adherence to lithium treatment (30-50%) Lithium narrow therapeutic range(0.8-1.1 mmols/l) necessity of constant monitoring of plasma lithium levels heart, kidney, thyroid function extremely toxic! -1.5-2.0 mmol/liter anorexia, vomiting, diarrhea, tremor, ataxia, confusion, sleepiness. - 2.0 mmol/liter impaired consciousness, convulsions lethal in overdose hemodialysis Adverse effects and toxicity of lithium impairment, thirst, nausea acne, loose stools tremor goiter, hypothyroidism polyuria and polydipsia edema weight gain teratogenic Drug interactions Many medications interact adversely with Lithium 1. carbamazepine 2. antipsychotics (haloperidol) 3. cardioactive drugs ( digoxin, angiotensinconverting enzyme inhibitors) 4. diuretics: thiazides and ACE inhibitors 5. nonsteroidal anti-inflammatory drugs Carbamazepine antiepileptic drug reasonable alternative to lithium used to treat acute mania, mixed state and also for prophylactic therapy The mode of action is like of lithium possible mediated via effects on secondmessenger systems Carbamazepine used alone or in combination with lithium. Carbamazepine potent inductor of hepatic cytochrome P450 isoenzyme system Carbamazepine induces its own metabolism! many drug interactions: 1. Lithium- increases the neurotoxicity of carbamazepine. The combination of lithium and carbamazepine -more effective than either drug alone. 2. Antipsychotics - drowsiness and ataxia 3. TCAs - concentration 4. MAOIs - cheese reaction Adverse effects of carbamazepine drowsiness, diplopia, nausea, rashes headache weight gain teratogenesis hematologic disturbances (agranulocytosis, leucopenia) The plasma concentration of carbamazepine must be monitored! Valproic acid (valprote) an antiepileptic with antimanic effects some patients who have failed to respond to lithium Adverse effects: - gastrointenstinal effects(nausea, vomiting, diarrhea), - CNS effects (sedation,tremor) - hematological effects (thromobocytopenia, leucopenia) - Hair loss Mode of actions: enhance the syntesis and release of GABA Divalproex sodium mixture of valproate sodium and valproic acid bioavailability and tolerability low drug-drug interaction no proven long term risk fewer gastrointestinal side effects Lamotrigine an antiepileptic well tolerated in bipolar affective disorder role in treating the depressive phase of the illness