Pharmacology Flashcards
Drugs that can cause lung fibrosis?
- Amiodarone
- Cytotoxic agents: busulphan, bleomycin
- Anti-rheumatoid drugs: Methotrexate, Sulfasalazine
- Nitrofurantoin
- ergot-derived dopamine receptor agonists (bromocriptine, cabergoline, pergolide)
Symptoms and signs of opioid misuse?
- Rhinorrhoea
- needle track marks
- Pinpoint pupils
- Drowsiness
- Watering eyes
- Yawning
overdose may lead to respiratory depression and death
What is the emergency management of opioid overdose?
IV or IM Naloxone: has a rapid onset and relatively short duration of action
Drugs for opioid detoxification?
NICE recommend methadone or buprenorphine as the first-line treatment in opioid detoxification
What are the features of digoxin toxicity?
Toxicity may occur even when the concentration is within the therapeutic range.
- generally unwell, lethargy,
- nausea & vomiting, anorexia, confusion,
- yellow-green vision
- arrhythmias (e.g. AV block, bradycardia)
- gynaecomastia
Management for digoxin toxicity?
Digibind is the first line treatment for severe digoxin toxicity.
- Correct arrythmias
- Monitor potassium
What are the adverse effects of Gentamicin?
Ototoxicity
- due to auditory or vestibular nerve damage
- irreversible
Nephrotoxicity
- accumulates in renal failure
- the toxicity is secondary to acute tubular necrosis
- concomitant use of furosemide increases the risk
- lower doses and more frequent monitoring is required
Gentamicin is a type of aminoglycoside antibiotic. It is poorly lipid-soluble and is therefore given parentally (e.g. for infective endocarditis) or topically (e.g. for otitis externa).
ECG changes seen in tricyclic antidepressant overdose?
TCAs: Amitriptyline and dosulepin (dothiepin) are particularly dangerous in overdose.
Features of severe poisoning include:
- Arrhythmias
- seizures
- metabolic acidosis
- coma
ECG changes include:
- sinus tachycardia
- widening of QRS
- prolongation of QT interval
Side effect of Nidfedipine, amlodipine (CCBs)?
Ankle swelling
Flushing
Headache
Finasteride is used in which conditions? What are its adverse effects?
Benign prostatic hyperplasia
Male-pattern baldness
- impotence
- decrease libido
- ejaculation disorders
- gynaecomastia and breast tenderness
Finasteride is an inhibitor of 5 alpha-reductase, an enzyme which metabolises testosterone into dihydrotestosterone thus reducing the production of dihydrotestosterone and therefore shrinking the prostate.
What are the adverse effects of amiodarone?
- Thyroid dysfunction: both hypothyroidism and hyper-thyroidism
- corneal deposits
- Pulmonary fibrosis/pneumonitis
- Liver fibrosis/hepatitis
- peripheral neuropathy, myopathy
- photosensitivity
- ‘slate-grey’ appearance
- thrombophlebitis and injection site reactions
- bradycardia
- lengths QT interval
Which drugs are P450 enzyme inducers?
CRAP GPS
Carbamazepine
Rifampicin
Alcohol chronic use
Phenytoin
Griseofulvin
Phenobarbitone
Sulphonyureas, St. John’s Wort
Which drugs are P450 enzyme inhibitors?
SICKFACES.COM
Sodium valproate Isoniazid Cimetidine Ketoconazole Fluconazole Alcohol acute use Chloramphenicol Erythromycin Sulfonamides
Ciprofloxacin
Omeprazole
Metronidazole
Grapefruit juice
Heparin overdose is reversed using?
Heparin overdose may be reversed by protamine sulphate, although this only partially reverses the effect of LMWH.
What are the features of lithium toxicity?
- Coarse tremor (a fine tremor is seen in therapeutic levels)
- Hyperreflexia
- Acute confusion
- Seizure
- Coma
Lithium is a mood stabilising drug used most commonly prophylactically in bipolar disorder. It has a very narrow therapeutic range (0.4-1.0 mmol/L) and a long plasma half-life being excreted primarily by the kidneys
What is the management of lithium toxicity?
- Mild-moderate toxicity may respond to volume resuscitation with normal saline
- Haemodialysis may be needed in severe toxicity
sodium bicarbonate is sometimes used but there is limited evidence to support this.
By increasing the alkalinity of the urine it promotes lithium excretion
What are the features of beta blocker overdose? and management?
- Bradycardia
- Hypotension
- Heart failure
- Syncope
Management:
- if bradycardic then Atropine
- in resistant cases glucagon may be used
What is the management for paracetamol overdose?
The minority of patients who present within 1 hour may benefit from activated charcoal to reduce absorption of the drug.
Acetylcysteine should be given if:
- There is a staggered overdose (all the tablets were not taken within 1 hour) or there is doubt over the time of paracetamol ingestion, regardless of the plasma paracetamol concentration
OR
- The plasma paracetamol concentration is on or above a single treatment line joining points of 100 mg/L at 4 hours and 15 mg/L at 15 hours, regardless of risk factors of hepatotoxicity
Acetylcysteine is now infused over 1 hour (rather than the previous 15 minutes) to reduce the number of adverse effects. Acetylcysteine commonly causes an anaphylactoid reaction, treated by stopping the infusion, then restarting at a slower rate.
Adverse effects of metformin?
- Gastrointestinal upsets are common (nausea, anorexia, diarrhoea), intolerable in 20%
- Reduced vitamin B12 absorption - rarely a clinical problem
- Lactic acidosis with severe liver disease or renal failure
Metformin may cause lactic acidosis if taken during a period where there is tissue hypoxia. Examples include a recent myocardial infarction, sepsis, acute kidney injury and severe dehydration
Which drugs should be avoided in renal failure?
- Antibiotics: tetracycline, nitrofurantoin
- NSAIDs
- Lithium
- Metformin
What are the features and management of salicylate (aspirin) overdose?
- Hyperventilation (centrally stimulates respiration)
- Tinnitus
- Lethargy
- Sweating, pyrexia
- Nausea/vomiting
- hyperglycaemia and hypoglycaemia
- seizures
- coma
Salicylate overdoses typically presents with a RESPIRATORY ALKALOSIS initially due to hyperventilation, followed by a METABOLIC ACIDOSIS due to lactic acid accumulation
Side effects of Rifampicin?
- Potent liver enzyme inducer
- Hepatitis
- Orange bodily fluids
- Rash
Side effects of Isoniazid?
- Peripheral neuropathy: prevent with pyridoxine (Vitamin B6)
- Hepatitis, agranulocytosis
- Liver enzyme inhibitor
Side effects of Pyrazinamide?
- Hyperuricaemia causing gout
- Arthralgia
- Hepatitis
Side effect of Ethambutol?
- Optic neuritis: check visual acuity before and during treatment
- Colour blindness.
It should be discontinued if these symptoms develop. In clinical practice Pyridoxine (vitamin B6) is given concurrently with ethambutol to try to prevent these side effects.
How to calculate breakthrough analgesia?
Breakthrough analgesia should be administered at 1/6th of the total daily opioid dose.
What are the features of organophosphate poisoning?
Features can be predicted by the accumulation of acetylcholine (mnemonic = SLUD)
- Salivation
- Lacrimation
- Urination
- Defecation/diarrhoea
- hypotension, bradycardia
- small pupils, muscle fasciculation
What is the dosage and route of adrenaline administered for anaphylaxis?
0.5ml 1:1,000 IM
What is the dosage and route of adrenaline administered for cardiac arrest?
10ml 1:10,000 IV or 1ml of 1:1,000 IV
What drugs need to be stopped when taking a macrolide?
Statins should be stopped whilst taking a course of macrolides. Macrolides inhibit the cytochrome P450 isoenzyme CYP3A4 that metabolises statins. Taking macrolides concurrently with statins significantly increases the risk of myopathy and rhabdomyolysis.
Erythromycin was the first macrolide used clinically. Newer examples include clarithromycin and azithromycin.
What drugs can cause an oculogyric crisis?
An oculogyric crisis is a dystonic reaction to certain drugs or medical conditions. Features:
- Restlessness, agitation
- Involuntary upward deviation of the eyes
- Antipsychotics
- Metoclopramide
- Postencephalitic Parkinson’s disease
Mx:
Intravenous antimuscarinic: Benztropine or Proocyclidine
