EMQ Part 2 Flashcards
Memantine
Mechanism of action
5HT1A partial agonist, MAO-B inhibitor, NMDA R antagonist, butylcholinesterase inhibitor, MAO-A inhibitor, GABA-B, 5HT 2A R stimulation, Alpha 2 agonist, 5HT1A partial agonist, GABA-A agonist
NMDA R antagonist
Side effect-Tolerance to hallucinogens
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, Alpha 1 adrenergic R blockade
5HT2A R desensitisation eg LSD
Benzodiazepine withdrawal symptoms
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, Alpha 1 adrenergic R blockade
Decreased brain GABA function. Benzo’s are GABA agonists. Bind to gamma sub-unit of GABA A R. Binding causes an allosteric modification of the R that results in an increase in GABA A receptor activity
Sedative action of trazodone
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism
H1 R antagonism
Postural hypotension with antipsychotics
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism
Alpha 1 R antagonism. Risperidone particularly ++
Constipation, dry mouth with TCA
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism
M3 antagonism
Irregular menstural periods with antipsychotics
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism
D2 antagonism
Haloperidol-induced NMS
Mechanism:
M3 R blockade, D2 antagonism, D2 R blockadeM1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism, 5HT2C,
D2 R blockade
Risks- young age, high potensy and high dose neuroleptic use, rapid increase in dose, depot medication, prior episodes of NMS, agitation, dehydration, exhaustion, organic illness, recent episode of catatonia
SSRI induced anorgasmia
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism
5HT2C agonism. Mirtazapine is a 5HT2C antagonist and hence indicated to treat sexual dysfunction with SSRI.
Mirtazapine augmentation for SSRI-induced sexual dysfunction: a retrospective investigation
Trazodone-induced priapism
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism, a2 R antagonism
A1 R antagonism
Mirtazapine-induced weight gain and sedation
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism
H1 R antagonism
SSRI induced GIT
Mechanism:
M3 R blockade, D2 antagonism, M1 R blockade, 5HT1A autoreceptor, 5HT2 R activation, H2 R antagonism. 5HT2A R desensitisation, decreased brain GABA function, H1 R antagonism, a1 R antagonism
5HT3 R agonism
In a case-control study looking at the association between the use of antihypertensive medication and depression, subjects with depression may be more likely to remember what medication they had had, due to the potential importance of this issue to them
Bias? Recall bias, Neyman’s bias, Selection bias, confounding bias, informatioin bias, unmasking bias, publication bias, membership bias, Barkson’s bias, Attrition bias
Recall bias
when cases and controls recall exposures differently.
Rumination bias or search for meaning bias is where people with diseases will think harder about their prior exposures than disease free people.
In a cohort study looking at the long term association between cannabis use and schizophrenia, subjects in the cannabis group were more likely to drop out of follow up.
Bias? Recall bias, Neyman’s bias, Selection bias, confounding bias, informatioin bias, unmasking bias, publication bias, membership bias, Barkson’s bias, Attrition bias
Attrition bias
A case-control study investigating the association, between poor social support and depression recruits, depressed subjects from psychiatric hospital in-patients
Bias? Recall bias, Neyman’s bias, Selection bias, confounding bias, informatioin bias, unmasking bias, publication bias, membership bias, Barkson’s bias, Attrition bias
Berkson’s bias . Hospital controls- usually higher response rates than population controls, but more likely to have sampling bias (hospital controls likely to have different exposures than population controls.)
Case-control study looking at smoking and Alzheimer’s disease shows a protective effect.
Bias? Recall bias, Neyman’s bias, Selection bias, confounding bias, informatioin bias, unmasking bias, publication bias, membership bias, Barkson’s bias, Attrition bias
Neyman bias: incidence-prevalence bias, selective survival bias. When a series of survivors is selected, if the exposure is related to prognostic factors, or the exposure itself is a prognostic determinant, the sample of cases offers a distorted frequency of the exposure.
Can occur in cross sectional and case-control.
Bias occurs only if the risk factor influences mortality from the disease being studied
In a placebod-controlled trial for a new antidepressant, group allocation is based on hospital numbers, so the psychiatrist who enters patients for the study knows in advance which treatment group they will be in.
Bias? Recall bias, Neyman’s bias, Selection bias, confounding bias, informatioin bias, unmasking bias, publication bias, membership bias, Barkson’s bias, Attrition bias, membership bias
Selection bias. The selection bias in an RCT is called allocation bias. Allocation concealment is necessary to minimise allocation bias
Priapism
R mechanism? 5HT1D stimulation, 5HT1A stimulation, 5HT3 stimulation, 5HT2A/2C antagonism, D2 blockade, a1 blockade, a2 blockade
A1 blockade
Obsessive-compulsive symptoms with antipsychotics
R mechanism? 5HT1D stimulation, 5HT1A stimulation, 5HT3 stimulation, 5HT2A/2C antagonism, D2 blockade, a1 blockade, a2 blockade
5HT1D stimulation. Acting on the autoreceptors, to reduce serotonin fucntion. May explain delay in optimal beneficial effects of SSRIs
Weight gain
R mechanism? 5HT1D stimulation, 5HT1A stimulation, 5HT3 , 2C antagonism, stimulation, 5HT2A/2C antagonism, D2 blockade, a1 blockade, a2 blockade
5HT2C
Most associated with weight gain. H1, H3 autoreceptors also. M3 in pancreatic beta cell, mostly due to SGA, induces alterations in glucose metabolism, due to reduction in insulin secretion and increased insulin resistance. SGA also stimulate ghrelin release. Also stimulate orexin from lateral hypothalamus, which increases appetite,. Orexin stimulated due to blockade of histaine receptors.
Leptin levels which control insulin sensitivity, increade by SGA. Ziprasidone is a potent 5HT1A R agonist and modest 2C R antagonist, which along with reuptake inhibition of serotonin and NE, potentially increase metabolic rate and decreases appetite.
GI side effects with SSRIs
R mechanism? 5HT1D stimulation, 5HT1A stimulation, 5HT3 stimulation, 5HT2A/2C antagonism, D2 blockade, a1 blockade, a2 blockade
5HT3 stimulation
Temporal intermittent rhythmic dealta slowing
?HSE, CJD, Sub-acute sclerosing pan encephalitis, generalised anxiety, absence seizures, complex partial seizures, myoclonic epilepsy, metabolic encephalopathy
Herpes simplex encephalitis. Focal abnormalities or diffuse slowing may be observed. Periodic complexes and periodic lateralising epilpetiform discharges (PLEDs) in the proper clinical context, are strongly suggestive of HSE. PCR analysis of CSF for the detection of HSV DNA is now gold standard.
Bilateral synchronous high amplitude with wave slowing
?HSE, CJD, Sub-acute sclerosing pan encephalitis, generalised anxiety, absence seizures, complex partial seizures, myoclonic epilepsy, metabolic encephalopat
Subacute sclerosing pan encephalitis
3 Hz diffuse spike and wave activity?HSE, CJD, Sub-acute sclerosing pan encephalitis, generalised anxiety, absence seizures, complex partial seizures, myoclonic epilepsy, metabolic encephalopathy
Absence seizures
Agent that binds the receptor but produces the opposite pharmacological effect
?inverse agonist, presynaptic R, irreversible antagonist, partial agonist, full agonist, second messenger system, competitive antagonist, potency, non-competitive antagonist
Inverse agonist
Partial agonist have a weaker preference than an agonist fofr the same R. Inverse agonist has all the properties of a full agonist, shifts equilibrium in the opposite direction.
Anatgonist reduces the effect of an agonist by preventing it from binding to receptors. Antagonists do not have any effect in the absence of an agonist
Buspirone acts via this mechanism
?inverse agonist, presynaptic R, irreversible antagonist, partial agonis, full agonist, second messenger system, competitive antagoist, potency, non-competitive antagonist
5HT1A partial agonist
The degree of response of a partial agonist depends on availability of neurotransmitter in the vicinity. If large concentration, partial agonist can actually inhibit transmission.
Lithium’s postulated mechanism of action
?inverse agonist, presynaptic R, irreversible antagonist, partial agonis, full agonist, second messenger system, competitive antagoist, potency, non-competitive antagonist
Second messenger system
- Modulatioin of neurotransmitters likely readjusts balances between excitatory and inhibitory activities, and decreased glutamatergic activitiy may contribute to neuroprotection.
- Lithium modulates signals impacting on the cytoskeleton, a dynamic system contributing to neural plasticity, at multiple levels, including glycogen synthase kinase-3beta, cAMP K, PKC, which may be critical for the neural plasticity involved in mood recovery and stabilisation.
- Lithium adjusts signalling activities regulating second messengers, transcription factors and gene expression
These antagonists alter the receptor site so that effects cannot be reversed completely by increasing dose of agonist
?inverse agonist, presynaptic R, irreversible antagonist, partial agonis, full agonist, second messenger system, competitive antagoist, potency, non-competitive antagonist
Allosteric modulator
(Non-competitive antagonists)
Binds at a site distinct from active site. Conformational change, which alters the affinity of the receptor for the endogenous ligand.
Positive increase affinity whilst negative decrease the affinity
Reversible antagonist binds non-covalently, “washed out.” An irreversible binds covalently and cannot be displaced.
Tigabine
?Increased GABA B R density and neural responsiveness, u R, cGMP, inhibition of GAT-1, prolonged sodium and calcium channel activation, adenosine R, inhibitioin of kainate mediated conductance at AMPHA glutamae R
Inhibition of GAT-1 Tiagabine is a potent inhibitor of GABA uptake into neurons and glial cells by inhibiting the GABA transporter
Caffeine
?inverse agonist, presynaptic R, irreversible antagonist, partial agonist, full agonist, second messenger system, competitive antagonist, potency, non-competitive antagonist, cGMP
Adenosine receptors. Mechanism of action
- Mobilisation of IC calcium and inhibition of specific phosphodiesteraes only occur at high non-physiological concentrations of caffeine.
- Antagonism at the level of adenosine receptors
- Caffeine increases energy metabolism throughout the brain but decreases at the same time cerebral blood flow, inducing a relative brain hyperperfusion
Involved in sexual arousal
?inverse agonist, presynaptic R, irreversible antagonist, partial agonist, full agonist, second messenger system, competitive antagonist, potency, non-competitive antagonist, cGMP
cGMP
Carbamazepine
?inverse agonist, presynaptic R, irreversible antagonist, partial agonist, full agonist, second messenger system, competitive antagonist, potency, non-competitive antagonist
Prolonged sodium and calcium activation. Inhibits sustained repetitive firing by blocking use-dependent sodium channels. CYP3A4. CYP3A4 is the priary isoform respondible for the formation of carbamazepine -10,11 epoxide. This metabolite is active and shown to be equipotent to carbamazepine as an anticonvulsant.
Topiramate
?inverse agonist, presynaptic R, irreversible antagonist, partial agonist, full agonist, second messenger system, competitive antagonist, potency, non-competitive antagonist
Inhibition of kainate mediated conductance at AMPA glutamate R, considered to produce its antiepileptic effect through several mechanisms, including modification of Na and Ca dependent action potnetials, enhacement of GABA-mediated Clo-fluxes into neurons, and inhibition of kainate-mediated condictance at glutamate R of the AMPA/kainate type. Vigabatrin is a selective and irreversible GABA transaminase inhibitor that greatly increases whole-brain levels of GABA
Non-opioid present up to 48 hours
Time in urine
?Phenylcyclidine, benzodiazepine, cannabis, alcohol, cocaine, heroin, codeine, morphine, amphetamine, methadone
Amphetamine
Time in urine: Marijuana Opiates Benzo's Alcohol
Marijuana -single: 3 days -moderate: 5-7 days -daily: 10-15 days -long term heavy: >30 days Opiates -codeine 48 hrs -heroin 2-4 days -morphine 48-72 hrs -oxycodone 2-4 days Benzo's -short-acting 3 days -long-acting 30 days Alcohol -7-12 hrs Amphetamine -48 hours
Opioid present for 3 days or more
Methadone
Present in urine for up to 8 days
Phenylcyclidine
Rewarding and aversive qualities of sensations are represented in this area
?Substantia nigra, periaqueductal grey, anterior cingulate, locus coeruleus, subthalamic nucleus
orbitofrontal cortex, hippocampus, amygdala, VTA
VTA
midbrain, situated adjacent to SN
dopaminergic neurons
Area is activated in tasks involving cognition and motor tasks
?Substantia nigra, periaqueductal grey, anterior cingulate, locus coeruleus, subthalamic nucleus
orbitofrontal cortex, hippocampus, amygdala, VTA
Anterior cingulate
1. detection of errors or shortfalls from some standard
2. Anticipation and preparation before task performance
3. Regulation of emotions
connects t the PFC, parietal cortex and both motor and visual systems
Damage to this area leads to amnesic syndrome
?Substantia nigra, periaqueductal grey, anterior cingulate, locus coeruleus, subthalamic nucleus
orbitofrontal cortex, hippocampus, amygdala, VTA
Hippocampus
This area is involved in mediating the flight/fight response
?Substantia nigra, periaqueductal grey, anterior cingulate, locus coeruleus, subthalamic nucleus
orbitofrontal cortex, hippocampus, amygdala, VTA
Amygdala
A substance found in the neuron type A, which is secreted from it, acts on neuron B
Neurotransmitter
Peptide secretions from neurons that are secreted directly into the blood stream that also act on other neurons as neurotransmitters
Neurohormone
A substance that influences neuronal activity and originates from non-synaptic sites
Neuromodulator
Post-synaptic compounds that participate in the generation of post-synaptic responses
Neuromediator
Substances released by post-synaptic structures, which maintain pre-synaptic neuronal structure
Neurotrophin
Survival, development and function of neurons
Ligand gated ion channels which are inhibitory and concentrate at the inhibitory synapses of the brain
?NMDA, Kainate, Glycine receptors, GABA R, muscarinic R, AMPA, Glutamate
GABA R
Acetylcholine, Glutamate also of this type
Ligand gated ion channel which are excitatory and is the major binding site for phenylcyclidine
?NMDA, Kainate, Glycine receptors, GABA R, muscarinic R, AMPA, Glutamate
NMDA
G protein coupled receptors that exist in 5 subtypes situated on the CNS and peripheral tissues
Muscarinic R
This receptor is involved in a type of encaphlitis and is associated with ovarian tumours
NMDA
Prodromal phase- fever, headache, URTI, NVD.
over 2 weeks develop psychiatric sx- insomnia, delusions, hallucinations, paranoia, autonomic instability, apathy and depression.
Catatonic sx, seizures, abnormal movements, autonomic instability, memory deficits,
GluN1 subunit of NMDAR
Beta adrenoreceptor agonist that has tremors as side effect
?Black widow spider venom, partial nicotinic agonist, acetylcholinesterase, verenicicline, lofexidine, xanomeline, salbutamol,L-Dopa, disulfuram
Salbutamol
Drugs acting through this mechanism are currently in development for treatment negative symptoms in schizophrenia
?Black widow spider venom, partial nicotinic agonist, acetylcholinesterase, verenicicline, lofexidine, xanomeline, salbutamol,L-Dopa, disulfuram
Partial nicotinic agonists
The alpha 7 nicotinic acetylcholine receptor gene CHRNA7, is associated with genetic transmission of schizophrenia and related cognitive and neurophysioogical sensory gating deficits. Cognitive dysfunction is responsible for significant psychosocial disability in schizophrenia. Nicotine, a low potency agonist at the alpha 7 R has some positive effects on neurophysiological and neurocognitieve deficits associated with schizophrenia, which suggests that moree effective receptor activation might meaningfully enhance cognition in schizophrenia.
Nicotinic receptor agonist which can cause neuropsychiatric side effects
?Black widow spider venom, partial nicotinic agonist, acetylcholinesterase, verenicicline, lofexidine, xanomeline, salbutamol,L-Dopa, disulfuram
Verenicicline
high affinity and high selectivity for binding at the a4B2 receptor and is a partial agonist at the receptor.
This substance causes a rapid release of acetylcholine
?Black widow spider venom, partial nicotinic agonist, acetylcholinesterase, verenicicline, lofexidine, xanomeline, salbutamol,L-Dopa, disulfuram
Black widow spider venom
This neuropeptide increase appetite, leads to weight gain and promote slow wave sleep in humans
?Oxytocin, vasopressin, orexin, BDNF, neurotensin, ghrelin, CCK, CRF, leptin, NPY
Ghrelin
Released from the paraventricular nucleus of the hypothalamus, elevated levels of this substances are found in depression
?Oxytocin, vasopressin, orexin, BDNF, neurotensin, ghrelin, CCK, CRF, leptin, NPY
Corticotrophin released factor
++corticosteroid secretion endangers neurons in the hippocampus, amygdala, and PFC, by increasing their vulnerability to oxidative stress.
Part of the neuropeptide family, this chemical is labelled as the social neuropeptide because of its ability to regulate social recognition, affiliation, modulation of anxiety, mood and aggression
?Oxytocin, vasopressin, orexin, BDNF, neurotensin, ghrelin, CCK, CRF, leptin, NPY
Oxytocin
A deficiency of this substance is found in narcolepsy. The neurons secreting this substance cease discharge during sleep
?Oxytocin, vasopressin, orexin, BDNF, neurotensin, ghrelin, CCK, CRF, leptin, NPY
Orexin
Hypocretins
Produced in lateral hypothalamus. Orexin neurone project to VTA, locus coeruleus and dorsal raphe. Narcolepsy shows low CSF orexin or hypocretin