How does glutamate cause calcium overload
Glutamate acts on metabotropic receptors -> Ca from ER
Activation of AMPA receptors which depolarises the cell (NA entry)
Depolarisation unblocks the NMDA Ca channels allowing entry
Results of calcium overload
Increases glutamate release
Activates proteases and lipases -> membrane damage
NO synthase -> ROS, hydroxyl radicals
Increases arachidonic acid release -> enhances free radical production and inhibits glutamate uptake
Oxidative stress
Mutations in SOD genes -> amyotrophic lateral sclerosis
TNFa activates superoxide dismutase catalase which converts O into O2 or H2O2
Stroke pathogenesis
85 ischaemia, 15 haemorrhagic Lack of blood causes calcium overload Rapid loss of neurons No ATP stops the NA+ Ca+ pump so there is overload ROS formed
5 treatments of stroke
Primary prevention- aspirin/warfarin
Recanalosation- tPA disperses clots if given in 3 hours. Plasminogen -> plasmin which breaks down clots
Neuroprotection- glutamate antagonists, ROS scavengers, protease inhibitors. Blood supply difficult.
Secondary prevention- anti thrombin therapy to those at risk. Tachycardia as risk factors
Neuro repair- IPSC therapy
Alzheimer’s disease
Amyloid plaques
APP gene on chromosome 21
AB42 overproduced, forms plaques
APP -> b40 and b42 by y Secretase
Presenillin gene- affects the y Secretase complex
Alzheimer’s disease
Tau tangles
Phosphorylation of tau by kinases
Dissociates from micro tubules and forms paired helical filaments -> Neurofibrillary tangles
Hyper phosphorylated tau increases amyloid deposits
Impairs axonal transport
Results of Alzheimer’s
Loss of cholinergic neurons in basal forebrain
Affects ACH formation, degradation and action
Nicotinic ACH receptors reduced
Treatment of Alzheimer’s
Cholinesterase inhibitors (Tacrine). Can be hepatotoxic.
Donepezil- reduce AB formation and toxicity
Memantine- blocks NMDA, stops calcium influx
ACH receptor agonists??
Parkinson’s disease
Suppression of voluntary movements, ischaemia, virus.
Low dopamine in substantial nigra and corpus striatum
Loss of dopaminergic neurons
Cannot inhibit cholinergic neurons -> hyperactivity
Aggregation of a-synuclein in Lewy bodies
Levodopa and side effects
Often combined with peripheral dopa decarboxylase inhibitor
5-10% crosses blood Brain barrier
Peripheral dopamine -> nausea, dyskinesia
On off effect common between rigidity and hypokinesia
Fluctuation corrected with COMT inhibitors
Dopamine agonists
Bromocriptine inhibits prolactin release from pituitary
Perv oldie can cause heart valve disease
Replaced by D2/3 selective drugs
MAO-B inhibitors
Selegiline-Prevent dopamine degradation
Amantadine- originally antiviral drug. Increased dopamine release. Less effective but better side effects.
Acetylcholine antagonists
mACH receptors inhibit dopaminergic neurons
mACH antagonists- Atropine
Dry mouth, vision, urine retention
Only used in patients who are on dopamine antagonists for antipsychotic
Deep brain stimulation
Brain pacemaker- electrodes in globus pallidus
Implanted pulse generator below clavicle
High frequency impulses override tremors
Anxiolytics drugs
Antidepressants- SSRIs, TCAs and MAOIs
Benzodiazepines- acute anxiety. Combination therapy SSRI
Anti epileptics- for GAD
Antipsychotics- olazepne, more side effects
Buspirone- 5-HT1A agonist, only GAD
B-Adrenoreceptor antagonists- propranolol
Barbituates
Anxiety and insomnia
Thiopental to sedate animals
Meprobamate- binds to GABA. Can cause seizures
Benzodiazepines
Directly open GABA-A receptor chloride channel
Distinct from GABA binding site
Increases conduction of CL when GABA bound
Diazepam/Valium
Respiratory depression with alcohol. Can have severe withdrawal.
Rohypnol- prevent memories of event
Monoamine theory of depression
Deficit of noradrenaline and serotonin
Drugs with affect monoamine transmitters affect depression
Tricyclic antidepressant drugs
Non selective serotonin and noradrenaline reuptake inhibitors
Some block a2-Adrenoreceptors and increase transmitter release
Sedation, confusion, hypotension, atropine like. In overdose, coma, delirium
Contraindications- increase alcohol and anaesthetic effects. Anti hypertensive.
SSRIs
Selectivity for serotonin
Fluoxetine, paroxetine
Less atropine side effects
In combination with MAOs -> serotonin syndrome, tremor, hyperthermia, collapse
Monoamine oxidase inhibitors
Major depression who have not responded
Type A inhibitor- stops noradrenaline and serotonin
Type B inhibitor- stops phenylethylamine
Reversible selective- Moclobemide. Irreversible unselective- Phenelzine
Rapid sustained increase in monoamines
Increase tyramine induced BP increase (cheese)
Delayed down regulation of b-Adrenoreceptors and serotonin receptors
Mood stabilisers- Lithium
Narrow window
Nausea, tremor, renal effects. Thyroid enlargement. Weight gain.
Lithium toxicity- confusion, motor impairment, coma, convulsions
2 types of epilepsy
Partial- discharge locally, symptoms by Brain region
Generalised- whole brain
Epilepsy treatments
Completely controlled 75%
Phenytoin, carbamazepine
Also benzodiazepines
Enhance GABA action (inhibitory neurotransmitter)
Inhibit sodium and calcium channel function
Dopamine theory of schizophrenia
Amphetamine releases dopamine, can induce episode
Hallucinations side effect of L-dopa
D2 receptor agonists exacerbate symptoms
D2 receptor antagonists used for treatment
Glutamate theory of schizophrenia
NMDA receptor antagonists cause symptoms
Amphetamine only positive symptoms
Reduced glutamate concentrations in patients
Serotonin theory of schizophrenia
Originally based on LSD (partial 5-HT2A agonist) hallucinations
Serotonin modulates dopamine pathways (control release)
Combined with D2 antagonists
5-HT2A receptors are Gi coupled, decreases neuron excitation
Promethazine
Surgical sedation Reduces agitation and anxiety Can be antitussive (anti cough) Old antipsychotic, 1/10 potency of chloropromazine H1 and mACH antagonist
Chloropromazine
Dopamine D2 antagonist
Weight gain, sedation, hepatic failure and lover disease,
Acute dystonias, Tardive dyskinesias (involuntary movements)
Acute dystonias
Involuntary movement
Reversible after drugs stopped
Consequence of effects on nigrostriatal dopamine
Tardive dyskinesia
Disabling movements of face, toungue, trunk, limbs
Develops after months or years of drug
Irreversible, worse after treatment stopped
Unwanted effects of antipsychotics
Booking D2 receptors increases prolactin secretion Causes breast pain, swelling Constant side effect Sedation Atropine like effects Hypotension (a-Adrenoreceptors) Jaundice Leukopenia
Clozapine
Negative symptoms of schizophrenia
High agranulocytosis risk
Adjunct therapy
Thiopental anaesthetic
Intravenous barbiturate
NA salt, lipophillic
Long lasting hangover as accumulates in fat
Only used for induction
Etomidate anaesthetic
Rapidly metabolised, shorter hangover
Involuntary movement, nausea
Suppresses adrenal steroid production
Increases mortality
Propofol
Very rapid metabolised
Continuous infusion
Day care surgery
Inhalative anaesthetics
Blood/gas and oil/gas coefficients
May give toxic metabolites
Chloroform -> free radicals
Halothane -> Br
Nitrous oxide
Analgesic
Pro longed causes methionine synthase inhibition- bone marrow depression
Neuromuscular blockades
Atracurium
Blockers of ACH receptors
Cause muscle relaxation
Action and effects of cocaine as local anesthetiser
Inhibition of NA influx, block channels Higher efficacy in high pH Euphoria Inhibition of noradrenaline and dopamine uptake by transporters Hypersensitivity Cardiovascular depression, vasodilation
Class I antiarryhythmic drugs
NA+ channel blockers
Bupivacaine, lidocain
3 stages of analgesic drug administration
NSAIDS
Weak opiates
Opiates
NSAIDS mechanism (paracetamol etc)
Non steroidal anti inflammatory drugs
COX inhibitors
Anti inflammatory effects of COX2, unwanted gastrointestinal COX1
Decrease prostaglandins which sensitise to bradykinin to cause vasodilation
Excitotoxicity
Caused by the neurotransmitter glutamate Is toxic to neurons Causes stiff neck when given orally as taste enhancer Agonist produces neurotoxic lesions Induces calcium accumulation
Anti inflammatory effects of NSAIDs
Reduces prostaglandins
Stops vasodilation which stops oedema
Suppress inflammation and pain
COX converts Arachidonic acid -> prostaglandin H2
NSAIDs side effects
Gastrointestinal
40% mucosal damage
COX1 -> prostaglandins that protect mucosa and reduce acid
Inhibits antithrombic prostacyclin PGI2 vasodilator
But does not affect prothrombic thromboxane TXA2
Skin reactions - Stevens Johnson- severe rash, cell death, epidermis seperation
Inhibit PGE2, PG12 prostacyclin synthesis -> renal failure
Meloxicam is COX2 specific
All may prolong bleeding, overdose causes liver failure
Aceytlsalicylic acid (aspirin)
Inhibits platelet aggregation
Anticoagulant- because irreversible and targets COX1 more, stops thrombosis
Tinnitus, nausea
Not used in gout- lowers urate excretion
Reye’s syndrome- associated with virus. Rash, sick, liver damage. Severe encephalopathy -> fatal 20-40%
Paracetamol
Anomaly- reduces both pain and fever. Inhibits prostaglandin synthesis in CNS Low anti inflammatory Selective COX2? No inhibition of platelets -> glucurinide or sulphate in liver
High doses -> kidney damage
Liver toxicity- n-Acetyl-p-benzoquinone imine. Cured by Acetyl cysteine
Coxibs
Selective COX2 inhibitors
Celecoxib and etoricoxib
Headache, rash, oedema
Not given to patients with ulcers as need COX2
2 types of chronic pain
Hyperalgesia- increased pain with mild stimulus
Allodynia- pain evoked by non-noxious stimulus
Transmission of pain (ascending and descending)
From dorsal horn
Synapse in ventral and medial thalamus
Projections in the somatosensory cortex
Lesions in medial thalamus cause analgesia
Descending control transmission in dorsal horn (inhibitory)
PAG -> RVM -> dorsal horn
Stimulation of PAG causes analgesia
4 synthetics derivatives of morphine
Phenylpiperidine derivatives- more potent, faster acting
Methadone- similar conformation
Benzomorphan- different binding profile and side effects
Semisynthetic thebaine derivatives- less respiratory depression
Loperamide
Phenylperidine derivative Opioid receptor agonist Constipation Does not enter brain Inhibits peristalsis so used to inhibit diarrhoea
Opioid receptor mechanism
Gi/Go , types OP1-4
Opening of K channel into cell (hyperpolarisation)
Inhibit Ca channel. Inhibit adenylyl cyclase and activate MAP kinase
Pure agonists euphoria on u/OP3
Morphine action on CNS
8
Analgesia- Protein kinase C and NMDA (glutamate) receptor activation
Euphoria- u receptor agonists
Respiratory depression- u inhibition. Increased PCO2
Cough- inhibit coughing
Vomiting- 40%. action on medulla oblongata.
Pupillary constriction- u and k. Pinpoint poisoning.
GI tract- reduced motility, increased pressure,. Inhibited by atropine.
Histamine- histamine release, bad for athsma
Tolerance and withdrawal from morphine
Within 24hrs
cAMP reduction -> compensatory increase
Tolerance of drugs acting on same receptor
Methadone to control withdrawal, long half life avoids euphoria
Common phenylpiperidine derivatives
Pethidine- no sedation, anti muscarinic, convulsions
Fentanyl- rapid onset, anaesthesia, transdermal
Common thebaine derivative
Buprenophine
Partial u agonist
Causes dysphoria
Less addictive
Tramadol
Weak u agonist
Dizziness, GI, no respiratory depression (preferable)
Inhibits noradrenaline uptake
Serotonin antagonist??
Opiate antagonists (reverse opiates)
Naloxane- inhibits all 3 receptors. No effect in normal healthy. Intravenous, rapid. Hyperalgesia in response to stress, as interferes with opioids
Naltrexone- longer duration, slow release implant
Co analgesics (analgesic side effects)
Glucocorticoids TCAs Anti epileptics Class I antiarryhythmic drugs Bisphosphonates - induce apoptosis in osteoclasts
Viral vaccinations
Cowpox immunised to small pox
Live vaccines- attenuated pathogens. MMR vaccine
Dead vaccines- inactivated virus e.g. Influenza
Antiviral chemotherapy
Viruses do not have own metabolism
Some enzyme can be used
Method of HIV infection
Symptoms
34mil infected
Infects CD4 helper T cells
Cytotoxic T cells induce apoptosis in normal cells
These T cells are killed by - cell lysis, apoptosis, Cd8 cells
Low CD4 levels causes AIDS
Fever, pharyngitis, myalgia, headache, rash, vomiting, lymphadenopathy
Reverse transcriptase inhibitors
3 types
Phosphorylated to give 5’-triphosphate derivative
Competes with triphosphate in DNA synthetis by transcriptase
Incorporation causes chain termination
Nucleoside reverse transcriptase inhibitor
AZT- 65% conc in CSF.
Nucleotide analogue reverse transcriptase inhibitor
Tenofovir- combination therapy. 2yrs +.
Non nucleoside reverse transcriptase inhibitor
Bind to catalytic site of enzyme. Most alter liver CytP450 enzymes
Nevaprine- penetrates CSF. Prevents mother to baby
HIV fusion inhibitors
CCR5 receptor antagonist- maraviroc
Inhibits R5 virus’s
Enfuvirtide- binds and inhibits gp41, involved in entry pore formation
Integrase inhibitors of HIV
Raltegravir- targets Integrase. Metabolised by glucurinidation.
Protease inhibitors of HIV
MRNA -> poly proteins -> cleavage
Protease not present in host, stops cleavage
Ritonavir- in activase proteases, combined with reverse transcriptase inhibitors
Highly active antiretroviral therapy
Reverse transcriptase inhibitors + protease inhibitors
Rapid resistance development- no proofreading of DNA
Resistance monitoring and patient adherence critical
Motioned by T cell count, virus genotyping
Treatment after anticipated exposure- decreases transmission 90%
HIV diagnosis tests
ELISA - antigens from sample, antibodies added. Antibody is linked to enzyme, substrate is added to diagnose how much enzyme/antibody bound. Colour change.
Western blot- separates antigens on weight
Rapid test- immunoblot. In 30mins.
Patient cured of HIV
Haematopoetic stem cell transplant with CCR5 delta32 mutation
Herpes simplex virus
dsDNA Enveloped HSV-1 and HSV-2 cold sores and genital herpes Regular reactivation Mother to child transmission
Antivirals for herpes simplex
Aciclovir- converted to acyclo-guanosine monophosphate
Phosphorylated 3x by kinases
Causes chain termination
36% resistant in immunocompromised
Resistance- thymidine kinase and DNA polymerase mutations
Foscarent- inhibits pyro phosphate site of DNA polymerase.
Cidofovir- acyclic nucleoside phosphonate. Lots of viruses. Used with probenecid which decreases renal clearance
Varizella zoster virus
Chickenpox- can induce Reye’s syndrome with aspirin
Adults treated with aciclovir
Causes foetal varicella syndrome -> brain and eyes
Shingles- reactivation. Analgesics, aciclovir
Vaccine- live attentuated. Higher dose prevents shingles.
Human cytomegalovirus
dsDNA
TORCH infection, leads to congenital abnormalities (50% transmission)
80-90% with symptoms suffer from hearing loss, vision and mental retardation
Hepatitis, retinitis, colitis, pneumonitis
Ganciclovir- 3x phosphorylated by UL97 kinase
90% resistance due to UL97 mutation
Name the 5 types of herpes virus
HSV-1 HSV-2 Varicella zoster Epstein Barr Cytomegalovirus
Influenza
Orthomyxoviruses
-sense RNA
Lower respiratory tract
Replication of Influenza A
Haemagglutinin binds to silicon acid residues
Uncoating
Synthesis of viral RNA and proteins
Liberation, antigenic drift and shift
Influenza A adamantanes
Neuraminidase inhibitors
Block M2 receptors, protons cannot flow in
Amantadine and rimantadine
High resistance, 80% in children
Neuraminidase inhibitors
Stop virus binding to sialic acid
Zanamir (dry powder), tamiflu (H1N1 100% resistant)
Influenza vaccine
Split vaccine (types A and B) Yearly vaccination (antigenic drift)
Hepatitis C virus
Positive sense ssRNA, enveloped
Replicates in hepatocytes
Chronic infection -> cirrhosis and cancer
Treatment of hepatitis C
PEGylated Interferon a
6 genotypes, 2,3 more treatable than 4,5
Covalent attachment of PEG to interferon. Increases half life.
Stops protein synthesis, induced death, MHC expression
Ribavirin- prodrug -> RNA nucleotide analogue (A?)
Inhibits polymerases, IMP dehydrogenase
5 things that limit efficacy of cancer therapies
Drug adherence- patients do not take drugs. Reduced recurrence time to 52% Small window- limited targets Action unknown Complex Adaptable populations
Platinum drugs
Cisplatin Reacts with guanine Intra and inter DNA strand linking Inhibits mitosis Induces DNA repair or cell death
Tubulin binding agents
Vinca domain
Destabilising
Bind to Tubulin dimers, block mitosis
Vinca alkaloids- vincristine
Tubulin binding agents
Colchicines domain
Colchicine
Destabilising
Binds to dimers, stops assembly
Also used for gout
Tubulin binding agents
Taxiod domain binders
Stabilise micro tubules
Prevent disassembly and therefore mitosis
Taxanes and epothilones
Methotrexate
Folate antagonist
Stops thymidylate synthesis and therefore DNA synthesis
Cancer, autoimmune,
Oral, low lipid solubility
Can cause depression of bone marrow, damage to GI tract
Topoisomerase I and II inhibitors
1- intercalates and stops single strand breaks, stops replication
2- etoposide forms complex with DNA and TI2 and prevents relegation after double strand break. Anthracyclins form complex with TI2 and prevent reselling.
Cancer therapy
How are cancer cells primed for death
Pro apoptotic signal
BLC2, activators bind (bim, bid)
Bax and Bak, activators bind
Pores form and CytC leaks
Apoptosis as a cancer drug target
TRAIL receptor activation
Caspase 8 expressed -> Bcl-2 -> caspase 3 -> apoptosis
Caspase 8 activation- interferons, retinoic acid
cFLIP (cap8 inhibitor) inhibitors- mTOR inhibitors, HDAC inhibitors
Anti Bcl-2 protein antagonist- ABT-737/199
Adaptation of cancer populations
Clonal evolution- selection pressure causes mutation
Selection pressure- hypoxia, drugs, starvation
3 types of targeted anti cancer drugs
Tamoxifen- anti oestrogen. Metabolised by cytP450 into active
Antibodies- tagged with biotinylated radioactive ligand
Kinase inhibitors
Kinase inhibitor
Cetuximab and Panitumumab
Anti EGFR antibody
Colorectal cancer
With chemotherapy or after failed oxaliplatin
Kinase inhibitor
Gefitinib and Erlotinib
EGFR tyrosine kinase inhibitors
Reversible, inhibit ATP binding site
Lung cancer with EGFR mutation
Interfere with ABC transporters
Kinase inhibitors
Lapatinib and Afatinib
Dual HER2 and EGFR tyrosine kinase inhibitor
Lapatinib- competative. Interferes with ABC transporters.
Afatinib- irreversible inhibitor
Lung cancer, EGFR mutation
Poly pharmacology
Interaction with multiple targets
Kinase inhibitor can increase efficacy of co administered drug
Multi targeted kinase inhibitor
Sunitinib
Renal cell carcinoma and gastrointestinal stroma tumour
First cancer drug approved for 2 indications
Inhibits angiogenesis and proliferation
Multi targeted kinase inhibitor
Imatinib
Inhibits bcr-abl protein (Philadelphia chromosome 22)
Targets ABL, c-KIT, PDGFR
Chronic myeloid leukaemia (22) treatment
Also GI stromal tumour
Drug repurposing for cancer
Methotrexate
Aspirin
Valproic acid (epilepsy)
Vemurafenib and resistance
Inhibitor of V600E mutated BRAF
50% response in metastasised melanoma
Resistance after 2-18 months