Doses that decide questions

Resuscitation

• Adult cardiac arrest: adrenaline 1 mg IV every 3 to 5 minutes, after the third shock in VF or pulseless VT, and as soon as possible in asystole or PEA. Amiodarone 300 mg after three shocks, then 150 mg after five.
• SVT: adenosine 6 mg rapid IV bolus, then 12 mg, then 18 mg, each with a flush. Verapamil if adenosine is unsuitable, for example in severe asthma.
• Bradycardia with adverse features: atropine 500 micrograms IV, repeated to a maximum of 3 mg.
• Shock that responds to fluid: 500 mL of crystalloid over less than 15 minutes, then reassess. In sepsis, 250 mL boluses up to 1000 mL.

Anaphylaxis

• IM adrenaline 1 mg/mL (1 in 1000) into the anterolateral thigh: 500 micrograms for adults and children over 12, 300 micrograms at 6 to 12 years, 150 micrograms at 6 months to 6 years, 100 to 150 micrograms under 6 months.
• Repeat after 5 minutes if airway, breathing or circulation problems persist.
• Fluids: 500 to 1000 mL of crystalloid in adults, 10 mL/kg in children.
• Antihistamines and steroids are not part of the first-line sequence.

Metabolic emergencies

• Hyperkalaemia with ECG changes: 10% calcium gluconate 30 mL IV over 10 minutes; insulin 10 units with 25 g of glucose; nebulised salbutamol 10 to 20 mg.
• Hypoglycaemia below 4 mmol/L: 15 to 20 g of fast-acting carbohydrate if conscious; 10% glucose 150 to 200 mL IV over 15 minutes, or glucagon 1 mg IM if there is no IV access.
• DKA: 0.9% sodium chloride, 1 litre over the first hour; fixed-rate insulin 0.1 units/kg/hour, with the usual long-acting insulin continued.
• Adrenal crisis: hydrocortisone 100 mg IV or IM at once.
• Symptomatic hypocalcaemia: 10 to 20 mL of 10% calcium gluconate, diluted, over 10 minutes with ECG monitoring.
• Seizures from low sodium: 150 mL of 3% saline over 20 minutes, aiming for a rise of about 5 mmol/L, and no more than 10 mmol/L in 24 hours.

Seizures

• Status epilepticus with IV access: lorazepam 4 mg IV, repeated once after 10 minutes.
• Without IV access: buccal midazolam 10 mg in adults. In children, 5 mg at 1 to 4 years.
• Second line: levetiracetam, phenytoin or sodium valproate, with senior help.

Poisoning

• Paracetamol: treat at or above a single line from 100 mg/L at 4 hours. Staggered or unknown timing means start acetylcysteine without waiting. SNAP regimen: 100 mg/kg over 2 hours, then 200 mg/kg over 10 hours.
• Activated charcoal within 1 hour of a significant ingestion, with a safe airway.
• Tricyclics: sodium bicarbonate when the QRS is above 100 ms.
• Opioids: naloxone, titrated IV, with observation because it wears off first.

Heart, brain and blood

• Suspected ACS: aspirin 300 mg as soon as possible.
• Ischaemic stroke: aspirin 300 mg for 2 weeks, then clopidogrel 75 mg daily long term.
• Secondary prevention: atorvastatin 80 mg after an MI or with peripheral arterial disease; atorvastatin 20 mg for primary prevention.
• Warfarin with a major bleed: IV vitamin K and prothrombin complex concentrate.
• Trauma with bleeding: tranexamic acid 1 g over 10 minutes, then 1 g over 8 hours, within 3 hours of injury.
• Burns: Parkland formula, 4 mL x kg x percent burn of Hartmann's over 24 hours, half in the first 8 hours from the time of the burn.

Lungs

• Acute asthma: salbutamol 5 mg nebulised; prednisolone 40 to 50 mg daily for at least 5 days (3 days in children); ipratropium 500 micrograms if severe; IV magnesium 1.2 to 2 g over 20 minutes if life-threatening.
• COPD exacerbation: prednisolone 30 mg daily for 5 days; amoxicillin, doxycycline or clarithromycin for 5 days if the sputum is purulent.
• Croup: a single dose of oral dexamethasone 0.15 mg/kg.
• Low-severity pneumonia: amoxicillin 500 mg three times a day for 5 days.
• Child pneumonia (3 months to 11 years, non-severe): amoxicillin for 3 days.

Infection

• Suspected meningococcal disease before hospital: benzylpenicillin IM or IV, 1.2 g at 10 years or over, 600 mg at 1 to 9 years, 300 mg under 1 year.
• Contacts of meningococcal disease: ciprofloxacin 500 mg once.
• Lower UTI in a woman: nitrofurantoin for 3 days if eGFR is 45 or more. In a man, 7 days.
• Pyelonephritis: cefalexin for 7 to 10 days.
• Cellulitis: flucloxacillin for 5 to 7 days.
• Sore throat needing an antibiotic: phenoxymethylpenicillin for 5 to 10 days.
• H. pylori: a PPI, amoxicillin and clarithromycin or metronidazole, twice daily for 7 days.
• C. difficile: oral vancomycin for 10 days.
• Chlamydia: doxycycline 100 mg twice a day for 7 days. In pregnancy, azithromycin 1 g, then 500 mg daily for 2 days.
• Gonorrhoea: ceftriaxone 1 g IM as a single dose.
• PID: ceftriaxone 1 g IM once, then doxycycline 100 mg and metronidazole 400 mg, both twice a day for 14 days.
• Early syphilis: benzathine benzylpenicillin 2.4 million units IM once.
• Shingles near the eye: aciclovir 800 mg five times a day for 7 days, with same-day eye review.
• Severe malaria: IV artesunate 2.4 mg/kg at 0, 12 and 24 hours, then daily.

Pregnancy and birth

• Folic acid: 400 micrograms daily until 12 weeks; 5 mg for higher-risk women. Vitamin D: 10 micrograms daily.
• Aspirin for pre-eclampsia risk: 75 to 150 mg daily from 12 weeks until the birth.
• Magnesium sulfate: 4 g IV over 5 to 15 minutes, then 1 g an hour for 24 hours.
• PPH: oxytocin 10 units IM or 5 units slow IV; carboprost 250 micrograms IM every 15 minutes, up to 8 doses; tranexamic acid 1 g IV.
• Chickenpox exposure in a non-immune pregnant woman: oral aciclovir 800 mg four times a day for 7 days, from day 7 after exposure.

Everyday prescribing

• Levothyroxine: 1.6 micrograms/kg daily under 65; 25 to 50 micrograms if older or with heart disease.
• Alendronate: 70 mg once a week, fasting, upright for 30 minutes.
• Vitamin D loading for deficiency: 50,000 units weekly for 6 weeks, or 4000 units daily for 10 weeks, then maintenance.
• B12 deficiency without neurological signs: hydroxocobalamin 1 mg IM three times a week for 2 weeks, then every 2 to 3 months.
• Starting oral morphine in palliative care: 20 to 30 mg a day in total, with 5 mg for breakthrough. Breakthrough is about one sixth of the 24-hour dose. Oral to SC morphine, divide by 2; oral morphine to SC diamorphine, divide by 3.
• Polymyalgia rheumatica: prednisolone 15 mg daily. Giant cell arteritis: 40 to 60 mg daily, started on suspicion.