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Pharmacology 6
Others
neuro
- anti-psychotics
- MAO-I’s
- MAO1
- MAO2
- non-selective
- issues
- increase activity of indirect alpha agonists
- use direct agonists with caution
- treat crisis with phentolamine
- tyramine
- increases release of NA, which can lead to hypertensive crisis
- serotonin syndrome
- withdrawal
- Interactions
- Tramadol, pethidine, high dose fentanyl
- increases 5HT activity —> agitation, hyperpyrexia
- WITHOLD FOR 2 WEEKS PRIOR TO AN ANAESTHETIC
- atypicial
- mirtazepine
- mixed agonist/antagonist at alpha adrenergic, D, H, 5HT and k-opioid receptors
- clozapine
- partial agonist at alpha, beta, H, 5HT and opioid receptors
- Tricyclics
- block SERT and NET
- Na and Ca channel blockers
- antimuscarinic SE’s
- Overdose
- sedation, convulsions, antimuscarinic effects (dry mouth, mydriasis), tachycardia, wide QRS, long QT
- e.g. amitryptilline
- SSRI’s
- typical
- epilepsy
- Na channels
- stabilise inactive fast channels
- phenytoin
- type Ib
- 90% PB, met. by liver, exc. in urine
- issues
- low therapeutic index
- zero order kinetics in high doses
- ‘PHENYTOIN’
- P450 inducer
- hirsuitism, hypotension/arrythmias
- enlarged gums
- nystagmus
- yellowing of skin
- teratogenicity
- osteomalacia
- ihibits
- intestinal conjugase —> folate deficiency
- insulin
- bone marrow
- neuro: brisk reflexes, vertigo, ataxia, headache
- carbamazepine
- 1st line for trigeminal neuralgia
- stabilise pre-synaptic channels
- GABA
- GABA agonists
- facilitators
- benzodiazepines
- barbiturates
- GABA transaminase inhibitors
- sodium valproate
- also stabilises Na channels
- teratogenic
- takes 2 weeks to be effective
- 90% PB
- met by liver, exc by kidneys
- vigabatran
- migraine
- sumatriptan
- 5HT-1 agonist
- treatment of ACUTE migraine
- can cause brady/tachy arrythmias
hypoglycaemics
- insulin
- increased by
- beta 2 stimulation
- theophylline
- leucine & arginine
- decreased by
- alpha 2 stimulation
- atropine
- types
- fast
- soluble insulin
- lispro (Humalog)
- slow
- glargine
- hexameric microcrystals delay absorption
- protamine zinc insulin
- isophane
- sulphonyureas
- actions
- increase Glycolysis
- bind to receptor on beta cells, increase Ca entry and increase RELEASE of insulin
- can cause hypoglycaemia
- protects beta cells from hyperglycaemic damage
- reduces Atheromatous build up
- increase glucose uptake into Muscle and fat
- ‘GRAM’
- examples
- chlopropramide
- gliclazide
- glibenclamide
- tolbutamide
- PK
- highly protein bound
- met by liver
- exc in urine
- issues
- avoid in pregnancy
- can cause pancytopaenia
- biguanides
- remember
- good for BIG people (as decreases weight)
- ‘fat and lazy’
- use what they’ve got (increased utilisation and glycolysis)
- slow absorption
- don’t bind
- don’t met
- actions
- increase utilisation of insulin by tissues
- increase rate of anaerobic glycolysis
- decrease gluconeogenesis
- increase glycolysis
- decrease weight gain, does not increase weight loss!
- decrease intestinal glucose uptake
- PK
- slowly absorbed
- BA 60%
- not protein bound
- not metabolised
- exc in urine
- T 1/2: 3 hours
- issues
- avoid in pregnancy
- lactic acidosis in renal failure
- ketonuria in young
- others
- thiazolidinediones
- acarbose
- meglitinides
- DPP-4 inhibitors
- GLP-1 mimetics
Others contd…
GI
- Antacids
- Citrate
- Magnesium
- Aluminium
steroids
- supplement when on > 10mg in last 3/12
- minor: routine dose OR 25mg hydrocortisone on induction
- moderate: routine dose PLUS 50mg hydrocortisone on induction, 100mg in divided doses for 1 day
- major: routine dose PLUS 50mg hydrocortisone on induction + 100mg in divided doses for 2-3 days
- 5mg pred = 750mcg dex = 750mcg betamethasone 4mg methylpred = 20mg hydrocort
antibiotics
- mechanisms
- destroy cell wall
- β-lactams
- penicillins
- mostly excreted unchanged in urine
- narrow
- little gram -ve cover
- fluclox, ben pen
- broad
- more gram -ve cover
- amox, amp
- anti-pseudomonal
- piperacillin, ticarcillin
- Beta-lactamase resistant
- cephalosporins
- mostly excreted unchanged in urine
- generations
- 1st
- 2nd
- 3rd
- gram -ve cover increases w. generations
- carbapenems
- mostly excreted unchanged in urine
- broadest cover, but limited vs. pseudomonas and MRSA
- meropenem
- imipenem
- monobactams
- aztreonam
- gram -ve, aerobic cover only
- glycopeptides
- broad gram +ve cover, limited gram -ve
- exc. unchanged in urine
- vancomycin
- teicoplanin
- RESISTANCE
- β-lactamase
- change in PBP structure
- inhibit protein synthesis (TMAC)
- tetracyclines
- inhibit 30s ribosome
- exc. 95% unchanged
- macrolides
- inhibit 50s ribosome
- similar gram +ve cover to penicillins, also mycoplasma and legionella
- met. and exc. by liver
- aminoglycosides
- inhibit 30s ribosome
- 1st line for severe gram -ve, some gram +ve
- chloramphenicol, clindamycin
- inhibit DNA synthesis
- ciprofloxacin
- inhibits DNA gyrase
- mainly gram -ve, some gram +ve
- exc. unchanged in urine
- metronidazole
- inhibits DNA synthesis
- exc. unchanged in urine
- disulfiram like reaction with alcohol
- rifampicin
- inhibits DNA dependent RNA polymerase
- trimethoprim
- inhibits dihydrofolate reductase
- nitrofurantoin
- peripheral neuropathy —> falls
- pulmonary fibrosis
- bacteria
- gram +ve (peptidoglycan wall stains violet/blue)
- cocci
- catalase +ve
- staph
- coagulase +ve
- coagulase -ve
- catalase -ve
- strep
- alpha-haemolytic
- s. pneumoniae
- s. viridans
- beta-haemolytic
- gamma (non)-haemolytic
- bacilli
- bacillus (anthrax), corynebacterium (diptheria), listeria, clostridium
- ‘Bacilli Can Live Claustrophobically’
- gram -ve (no wall, stain pink)
- cocci
- bacilli
- haemophilus, moraxella, pseudomonas, enterobacter (proteus, e.coli, klebseilla, salmonella, shigella), campylobacter
- ‘HM PEC (PEKSS)’
- anaerobes
- bacteriostatic/bacteriocidal
- ECSTaTiC
- erythromycin
- clindamycin
- sulphonamides
- tetracyclines
- trimethoprim
- chloramphenicol
- Very Proficient At Cell Murder
- vancomycin
- penicillins
- aminoglycosides
- ciprofloxacin + cephalosporins
- metronidazole