Therapeutics & Toxic 9 Flashcards
Gentamicin = aminoglycoside, poorly lipid soluble so must be given parentally
Adverse effects?
C/I?
Dosing?
- irreversible ototoxicity
- nephrotoxic
- C/I in myasthenia gravis
- if trough level high then increase dosing interval
Organophosphate insecticide poisoning = inhibition of acetylcholinesterase -> up regulation of nicotinic & muscarinic cholinergic neurotransmission
- features?
- Rx?
Salivation Lacrimation Urination Defecation/diarrhoea - also hypotension, bradycardia - small pupils, muscle fasciculation Rx = Atropine (pralidoxime role unclear)
Overdoses that can be dialysed?
Barbiturates Lithium Alcohols Salicylates Theophyllines
Quinolones inhibit DNA synthesis and are bactericidal
- MoA?
- MoResistance?
- adverse effects?
- C/I?
- inhibit DNA gyrase (topoisomerase II) & topoisomerase IV
- resistance by mutations to DNA gyros, efflux pumps which reduce intracellular quinolone conc
- lower seizure threshold
- tendon damage esp if taking steroids
- lengthens QT interval
- avoid in pregnancy, breastfeeding & G6PD
Amiodarone-induced hypothyroidism
- pathphys?
- what to do?
- high iodine content causing an autorgeulatory phenomenon where thyroxine formation is inhibited due to high levels of circulating iodide
- can continue amiodarone if this is desirable
Amiodarone-induced thyrotoxicosis type 1?
- XS iodine-induced thyroid hormone synthesis
- goitre
- Rx = Carbimazole/potassum perchlorate & stop amiodarone
Amiodarone-induced thyrotoxicosis type 2?
- amiodarone-related destructive thyroiditis
- no goitre
- Rx = corticosteroids
Poisonous snake in UK = adder/viper/viper berus
- can be extremely locally painful with systemic Sx, due to composition of venom (but also can have a bite without venom - still Sx)
- pain, swelling, erythema, paraesthesia, numbness, blood blistering
- tracking, compartment syndrome, tissue necrosis
- systemic Sx similar to anaphylaxis, can be delayed
- significant bruising
-> analgesia & supportive care
(tourniquet increases likelihood of localised necrosis & venous thrombosis, as well as arrhythmia)
- only for severe systemic envenomations in patients with resistant hypotension, new ECG changes, significant rise in white cell count, raised CK, metabolic acidosis or swelling involving more than half the affected limb or crossing a joint boundary - 20% have an anaphylactic reaction
Rx of paracetamol OD?
- activated charcoal if <1h ago
- NAC
- liver Tx
Rx of salicylate OD?
- haemodialysis if severe
Rx of benzodiazepine OD?
Flumazenil if severe or iatrogenic (has risk of seizures)
- otherwise supportive
Rx of tricyclic antidepressants OD?
- IV bicarbonate may reduce risk of seizures & arrhythmias in severe toxicity, to correct acidosis as 1st line of Rx
(1a 1c antiarrhythmics C/I, III avoid etc)
Rx of lithium OD?
- volume resuscitation
- haemodialysis if severe
(sodium bicarb may promote lithium excretion through increasing alkalinity)
Rx of heparin OD?
Protamine sulphate
Rx of beta-blocker OD?
- atropine if bradycardia
- glucagon if resistant
Rx of ethylene glycol OD or methanol poisoning?
- Fomepizole = inhibitor of ETOH dehydrogenase
- HD if refractory
Rx of Digoxin OD?
Digoxin-specific Ab fragments
Rx of iron OD?
Desferrioxamine, chelating agent
Rx of lead OD?
Dimercaprol, calcium edetate
Rx of cyanide OD?
Hydroxocobalamin, also combo of amyl nitrite, sodium nitrite, sodium thiosulfate
Drugs known to cause impaired glucose tolerance?
- steroids
- tacrolimus, ciclosporin
- IFN-alpha
- nicotinic acid
- antipsychotics
- thiazides, furosemide
- beta-blockers
Indications for dopamine receptor agonists?
Monitoring?
Adverse effects?
PD
prolactinoma/galactorrhoea
cyclical breast disease
acromegaly
- bloods & CXR before starting, and closely monitor with Echo due to risk of pulmonary, pericardial & retroperitoneal fibrosis
- nausea, vomiting, postural hypotension, hallucinations, somnolence
Drugs causing lung fibrosis?
amiodarone cytotoxics: busulphan, bleomycin anti-rheum: MTX, sulfasalazine, gold nitrofurantoin ergot-derived dopamine receptor agonists: bromocriptine, cabergoline, pergolide
Salicylate OD - acid-base picture?
features?
Rx?
indications for HD?
- mixed resp alkalosis & metabolic acidosis
- hyperventilation, tinnitus, lethargy, fever, sweating, nausea, vomit, hyperglycaemia & hypo, seizures, coma
- ABC, charcoal, sodium bicarb, haemodialysis
- serum conc >700
- metabolic acidosis resistant to Rx
- acute renal failure
- pulmonary oedema
- seizures
- coma
Tricyclic OD
- early features?
- if severe?
- ECG changes?
- Rx?
- dry mouth, dilated pupils, agitation, sinus tachycardia, blurred vision
- arrythmia, seizure, metabolic acidosis, coma
- sinus tachycardia, QRS widening, prolonged QT (>100 seizure >160 ventricular arrhythmia)
- IV bicarb
- IV lipid emulsion can help bind free drug and reduce toxicity
Novel psychoactive substances: Stimulants similar to MDMA, amphetamines, cocaine
examples?
- increased serotonin, dopamine, noradrenaline -> euphoria
- mephedrone = cathinone = bath salts, m-cat, meow meow
- benzylpiperazine = exodus, legal x, legal e
- pill/powder/snorted
- similar adverse effect profile to MDMA/cocaine, with risk of serotonin syndrome
Novel psychoactive substances: Cannabinoids which are synthetic agonists
- examples?
- ‘spice’
- sprayed onto herbal mixtures which are then smoked, also can be liquid
Novel psychoactive substances: Hallucinogenics examples?
dissociatives - similar effect to ketamine with a sense of not being connected to physical body/time = mexxy/methoxetamine - NMDA antagonist - tachycardia, HTN, mydriasis, confusion, agitation, nystagmus, dysarthria, ataxia
psychedelics - similar effect to LSD but may also be stimulant