Revision Flashcards
(39 cards)
Which antidepressant has sedating effect at lower rather than higher doses? MOA and SE
Mirtazapine. NaSSA. At lower doses it is primarily antihistaminergic causing sedation however at doses higher than 15mg it primarily causes the release of noradrenaline and is less sedating
Which Antidepressants are most sedating?
Tertiary amines – amitriptyline, clomipramine, imipramine and doxepin are the most sedating Secondary amines (amoxapine, desipramine, nortriptyline) are mildly sedating SSRIs (citalporam, escitalopram, flunarizine, fluvoxamine, paroxetine, sertraline, venlafaxine) have minimal sedation Atypical anti depressants – mirtazapine, trazodone, nefazodone are also potent sedatives NEFAZODONE: can significantly increase total REM sleep time Mirtazapine - sedative at lower doses, activating at higher doses
Which antidepressant is least likely to cause sexual dysfunction MOA and SE. Which can cause a painful prolonged erection?
Buprorion is probably the least likely antidepressant to induce sexual dysfunction. Bupropion is relatively safe and seizures are the predominant concern when taken in overdose MOA of bupropion is uncertain may be inhibition of presynaptic dopamine and norepinephrine reuptake transporters. Approved for MDD, SAD, Tabacco cessation Has a high propensity to precipitate seizures compared to other anti depressants Trazodone can cause priapism – urological emergency with cavernosa engorgement, whereas nefazadone can cause impotence
Side effects of MITOXANTRONE?
Nausea, vomiting, hair loss, immunosuppresion CARDIOMYOPATHY - irreversable
Carbamazepine with laryngeal injection – cause? MOA, SE, Inhibitors and inducers?
Carbamazepine SE: Hematologic toxicity including agranulocytosis, pancytopenia and aplastic anaemia, hyponatremia are possible SE Fever, pharyngitis, oral ulceration or ecchymosis should be watched for, Red throat suggests LEUKOPENIA St Johns Wort interacts through cytochrome P450 – carbamazepine, phenytoin, antiretrovirals, benzos, OCP, phenobarbitone, theophylline and warfarin Carbamazepine is an AUTO INDUCER – after 15-30 days the plasma clearance usually doubles
Differences between oxcarbazepine and carbamazepine
Closely related Oxcarbazepine is more likely to cause hyponatremia than carbamazeoine (in 2.5% of patients)
Renal stones on multiple AEDs – which is the culprit? MOA and SE
Topiramate is a weak carbonic anhydrase inhibitor. MOA for epilepsy – augmentation of GABA, antagonization of NMDA receptors Nephrolithiasis occurs 2-4 x more commonly Stone formation is promoted by reducing urinary citrate excretion and increasing urinary pH Concomittal use of topiramate with other carbonic anhydrase inhibitors or ketogenic diet also increases risk. Increase fluids Other SE: abnormal vision with acute secondary angle closure glaucome, acute myopia and suprachoroidal effisions – all reversible if recognised
What does phenytoin interact with?
Phenytoin metabolism is inhibited by isoniazid – results in phenytoin toxicity INH (Isoniazid) – (INHIBITOR) Valproate is another phenytoin enzyme inhibitor
Which AED can also be used for neuropathic pain MOA and SE
Gabapentin and pregabalin GABA modulates pain Gabapentin has been shown to reduce pain associated with diabetic neuropathy and post herpetic neuralgia
Indication for migraine prophylaxis Drugs approved?
3 or more headahces a week Commonly used medications – Strong evidence (divalproex, valproate, topiramate, metoprolol, propranolol, timolol. Moderate evidence – amitryptiline, venlafaxine, weak evidencece carbamazepine, oxcarbazepine, ACE inhibitors, ARBs, clonazepam. Conflicting evidence – calcium channel blockers – evidence against – lamotrigine. ACUTE TREATMENT: Triptans, DHE, aspirins, ibuprofen, naproxen, panadol + caffeine + aspirin, butorphanol nasal spray, prochloperaxine IV. Which to chose – SE dependend Propranolol – not if asthma Valproate – not in women of childbearing age Topiramate – think kidney stones and closed angle glaucoma
Treatment of neurocysticercosis?
Commonest cause of seizures worldwide Single enhancing lesions do well when treated with only anticonvulsants, some experts add ALBENDAZOLE (1 week) or PRAZIQUANTEL (2 weeks) Concommittal steroids can reduce oedema and is also recommended
What causes ragged red fiber myopathy?
Zidovudine Ragged red fibers are formed due to abnormal mitochondria with paracrystalline inclusions
Management of Wernicke’s
thiamine with glucose after Thiamine, high dose Wernicke’s can be precipitated by administering glucose to a patient with low thiamine levels ths give thiamine with or before glucose
AEDs and OCP- summarise
Barbiturates, carbamazepine, oxcarbamazapine, topiramate, phenytoin, primidone – all reduce efficacy of OCP Enhance cytochrome p450 metabolism, Increase metabalism of of oral contraceptive steroids Valproate and felbamate inhibit p450 Choices include: using another contraception or changing to non enzyme inducing pill Lamotrigine, levetiracetam, gabapentin and tigabine have no effect on pill
Which migraine treatment causes cardiac valvular fibrosis MOA and SE
Dihydroergotamine Pleural and retroperitoneal fibrosis in patients following prologed daily ise of injectable dihydroergotamine has been reported Pergolide is another ergot analogue which is usuually used in the treatment of PD and is associated with pleural and pulmonary fibrosis
How do statins cause myopathy
They block the production of farnesyl pyrophosphate, an intermediate in the synthesis of coenzyme Q10, which plays an important role in muscle energy production. It has been speculated that a reduction in ubiquinone in skeletal muscle may contribute to statin induced myopathy
MetalToxicities What do you look for in thallium, arsenic, lead, and ethylene glycol toxicities
Peripheral neuropathy + diffuse alopecia – chronic thallium toxicity Neuropathy, GI symptoms, anaemia, jaundice, brownish cutaneous pigmentation, hyperkeratosis of palms and soles, transverse banding of the nails (Mee’s lines) = arsenic poisoning Extensor paresis (wrist drop) and diffuse abdominal pain. Black line on gingival margins (Burton line) = lead toxicity Ethylene glycol – look very drunk +/- seizure and coma. Retinal toxicity. Metabolic acidosis, Hypocalcemia. Renal effects with stones
Causes of B12 Deficiency How does IF Abx cause peripheral neuropathy
Pernicious anaemia (75%) - anti-gastric intrinsic factor antibody formaton. Others – vegeterianism, H. pylori, breasffeeding infants of vegan mothers, alcoholism, dietary fads, Coeliac disease, enteritis, exudative enteropathy, intestinal resection, Whipple disease, sulphuric acid ingestion with secondary pyloric and duodenal obstruction Medications: colchicine, neomycin, p-aminosalicylic acid Subacute combined degeneration consists of patchy loss of myelin in the dorsal and lateral columns – several cofactors are necessary for the conversion of homocysteine to methionine and methylmalonyl-CoA to succinyl-CoA and when these cofactors are unavailable, abnormal levels of homocysteine are found in the blood and excessive methylmalonic acid MMA is accumulated and excreted in the urine. Excess MMA leads to the synthesis of abnormal fatty acids instead of mylein. Abnormal fatty acids are incorporated into the neuronal lipids leading to the formation f a fragile myelin sheath
TPN and parkinsonism- what is it?
Manganese induced parkinsonism has been shown especially in patients receiving high amounts of manganese via total parenteral nutrition
Treatment of bacterial meningitis- dexamethasone evidence ?
10mg within 20 minutes of first dose of Abx 10mg 6hrly for 4 days For suspected or proven pneumococcal meningitis – discontinue once another pathogen revealed
Valproate SE and drug interactions
Interacts with phenobarbital to increase levels
Neurotransmitter revision - what are 8 neurotransmitters and their locations
SEROTONIN - Dorsal raphe nucleu – fire tonically at a slow rate during waking then less in slow wave sleep and cease in REM s NOREPINEPHRINE - Locus ceruleus DOPAMINE - Limbic system Histamine and Orexins - hypothalamus ACETYLCHOLINE - basal forebrain HIStamine system - tuberomamillary nucleus of hypothalamus noradrenaline - locus ceruleus
Felbamate MOA / SE
Felbamate blocks NMDA receptor and potentiates GABA activity Severe SE – Aplastic anemia and liver failure are the most severe adverse effects of Felbamate. SE – mild CNS depression, nystagmus, ataxia, tachycardia, nausea and vomiting
Best AEDs in Liver dysfunction
Gabapentin is very liver safe, 100% renally excreted Levetiracetam is good in hepatic dysfunction
