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CSIM2 > CPTP4.12 > Flashcards

CPTP4.12 Flashcards

1
Q

Antibiotics to avoid in liver disease?

A

Chloramphenicol, erythromycin, tetracycline, pyrazinamide, nitrofurantoi.

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2
Q

Principles of prescribing in liver disease and some hepatotoxic drugs?

A

Paracetamol, aspirin, methotrexate, isoniazid, oral contraceptives, antibiotics. Avoid things that interfetre with haemostasis as this will already be disrupted, avoid sedatives and diuretics or drugs that cause constipation (HE). Use other routes of elimination. Avoid drugs that cause Na+ retention.

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3
Q

How can hepatic disease affect pharmacokinetics?

A

May lead to drug accumulation, failure to form active or inactive metabolites, increased bioavailibility after oral administration (i.e. reduced first pass metabolism), alteration in protein binding (hypoalbuminaemia) and renal function altered

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4
Q

What three things does hepatic drug clearance depend on?

A

Blood flow, fraction of free drug (therefore can interact with hepatic enzymes), intrinsic clearance (Clint) of that drug in the absence of limitations.

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5
Q

Extraction ratio?

A

Fraction of drug removed during one pass of the liver. Ratio of hepatic clearance to hepatic blood flow. Can be high (>0.7), int (0.3-0.7) or low (<0.3). High ER = large first pass effect therefore low bioavailibility. These drugs must therefore be reduced in cirrhosis (initial AND maintenance)

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6
Q

Significance of liver cirrhosis for low and high ER drugs?

A
  1. High ER (high hepatic extraction); get much higher maximal concentration and bioavailability. Need initial and maintenance reduced.
  2. Low ER just has higher bioavailibility (think of graph) so only need to reduce maintenance.
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7
Q

High ER and oral drug?

A

Reduce initial dose and maintance. Reduced dose = (normal dose * bioavailibility in health (1-ER))/100.

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8
Q

High ER and IV drug?

A

Only reduce maintenance dose (according to hepatic blood flow)

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9
Q

Low ER (first pass metabolism <30%) and low albumin binding?

A

Reduce maintenance dose or increase dosing interval. Intermediate extraction will also need maintenance adjusted.

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10
Q

Low ER and high albumin binding?

A

Reduce initial dose if albumin low, reduce maintenance dose.

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11
Q

Most dangerous pharmacokinetics in liver disease?

A

Oral, low bioavailbility, narrow Tw. Reduce dose and monitor!

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12
Q

Drugs causing dyspepsia type symptoms?

A

NSAIDs and steroids, bisphosphonates, CCBs, theophylline.

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13
Q

Antacids?

A

AlOH etc. Contain alkaline salts, raise pH. Bind and inactivate pepsin. AEs are constipation and diarrhoea, contraindicated (AlOH, MgOH2 in HYPOPHOSPHATAEMIA)

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14
Q

H2 antagonists?

A

Cimetidine, ranitidine. First line in PUD/GORD. Competively antagonise histamine (stop stimulation of parietal cells). Avoid cimetidine if on warfarin/phenytoin/theophylline as inhibits P450.

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15
Q

PPIs?

A

Irreversibly block H+/K+ATPase on parietal cells. Stop when on Abx (C.diff risk/gastroenteritis), electrolyte disturbances; interacts with clopidogrel. Can also cause hypomagnesaemia, acute interstital nephritis, microscopic colitis.

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16
Q

H. pylori eradication regimes?

A

PPI amoxicillin and metronidazole/clarithromycin. If fails, do quadruple therapy (omeprazole, two antibiotcs [tetracycline and metronidazole] and bismuth chelate. Give for 7 days and then retest!

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17
Q

Treating PUD?

A

Heal ulcer (antisecretory, can do IV PPI), H. pylori eradication, stop NSAIDs if possible, surgery if necessary.

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18
Q

Bulk forming laxatives?

A

Bran, methylcellulose, isphagula husk. Used when stool is small and hard. Increase volume and induce peristalsis. Contraindicate in dysphagia, intestinal obstruction, colonic atony (need peristalsis). AEs are flatulence, distention and obstruction. Good if dietary fibre cannot be increased. Must stay hydrated. Not good for opioid induced.

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19
Q

Osmotic laxatives?

A

Lactulose, macrogol. Used first line in hepatic encephalopathy. Increased water secretion into gut, then distend colon and cause peristalsis. Again, contraindicated in obstruction. AEs are flatulence, cramps, abdominal discomfort. Use with caution in elderly/renal impairment.

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20
Q

Stimulant laxatives?

A

Senna, bisacodyl, danthron and sodium picosulphate. Increase peristalsis (and water/salt excretion). Used to empty bowel before procedures. Good for short periods and opiate induced constipation. Again contraindicated in obstruction. Long term can give plexus damage and disrupt bowel function. Danthron only in terminally ill.

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21
Q

Faecal softeners?

A

Liquid paraffin and sodium docusate. Docusate softens stool, paraffin lubricates it. Long term, paraffin can impair absorption of fat soluble vitamins, and should not be used for under 3s. Treats constipation, impaction, haemorrhoids. Do not have laxative affect alone so need another laxative.

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22
Q

If have dyspepsia, and do H. pylori test?

A

If positive, and on NSAIDs, give two months PPI then eradication. If not on NSAID, eradication. If negative, give full dose PPI for 4-8 weeks.

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23
Q

Managing NSAID PUD risk?

A

Use COX-2 if possible, give PPI cover, low dose. Not COX-2 if have CVD.

24
Q

Short term constipation?

A

Give bulk forming and fluids; then if needed give osmotic, then stimulant.

25
Q

Opioid induced constipation?

A

Give osmotic and stimulant, not bulk forming!

26
Q

Faecal impaction?

A

Osmotic to soften, then try stimulant. May need enema.

27
Q

Chronic constipation?

A

Bulk forming, then try/add osmotic, then stimulant. Same as chronic really!

28
Q

If on aspirin and have PUD bleed?

A

Stop until haemostatically stable, then continue at low dose (want to prevent vascular events still).

29
Q

Management of diarrhoea?

A

Oral fluids are best. Aim is to restore fluids and electrolytes. If have to admit, get in isolation. If severely dehydrated and unable to drink, admit immediately for IVT. If have to use antimotility, use loperamide.

30
Q

Treat dyspepsia or investigate?

A

If over 55 or worrying symptoms, don’t give PPI, do 2ww (can’t be on PPI ideally for endoscopy). Otherwise, can test and treat for H. pylori, then review. Eradication therapy usually enough.

31
Q

Treating PUD?

A
  1. If H.pylori +ve, eradication therapy usually enough; may need antisecretory therapy for a further three weeks if ulcer large/complicated. If NSAID associated, give PPI until healed, then carry on.
32
Q

Investigating constipation?

A

Most does not need investigation; red flags are >40 with microcytic anaemia, weight loss/bleeding/mucinous discharge/tenesmus, new onset in elderly. Remember non-pharma treatments (diet, mobility, regular habit, hydration).

33
Q

Loperamide indications?

A

Mild infective diarrhoea, IBS, chronic IBD diarrhoea, high output stoma. Contraindicated in severe UC, C. diff, severe infective diarrhoea, dysentery, liver disease.

34
Q

Worst laxatives for obstruction?

A

Stimulants and bulk forming.

35
Q

B2 agonists in asthma?

A

Salbutamol, terbutaline (SABA); rapid onset, protects against cold/exercise. LABA = salmeterol/formeterol. Have lipophilic chain to anchor. Cause SM relaxation when bind to B2. AEs are tremor, anxiety, headache, muscle cramps, hypokalaemia, palpitations/tachycardia/arrhythmia/myocardial ischaemia.

36
Q

Muscarinic antagonists in asthma?

A

SAMA and LAMA. Second line. Competitively antagonise ACh at M3. Relax SM and decrease mucous. Useful if cannot tolerate B2 agonists e.g. IHD. An adjunct.

37
Q

Theophylline in asthma?

A

A methylxanthine. Inhibits phosphodiesterase to prevent cAMP degradation; more cAMP in cell so no constriction. Reverses steroid insensitivity and inhibits leuktriene synthesis. Acute BD and inhibits delayed phase. Narrow TW and many interactions; acts further downstream than other drugs. increased toxicity with erythromycin, quinolones. Toxicity gives CNS excitation, nausea. Remember, in acute asthma, if already on theophylline do NOT give loading dose

38
Q

Montelukast?

A

Leukotriene antagonist. Inhibits cysteinyl L1 receptor. Oral. Extensive biliary excretion. Approved for prophylaxis, not acute BD. Can be good for exercise induced asthma. Act further downstream than corticosteroids so less effective but fewer AEs.

39
Q

Corticosteroids in asthma?

A

Reduce inflammation and mucous. Inhaled AEs = candida and hoarseness. Usual systemic AEs. Can give orally (pred) or inhaled.

40
Q

Drugs which exacerbate asthma?

A

B-blockers (especially non-cardioselective; lungs are B2, heart B1 e.g. propanolol, timolol, even if given as eye drops!), adenosine (completely contraindicated), NSAIDs (bronchospasm if sensitive [roughly 15%]). Give clopidogrel instead of aspirin.

41
Q

Fluticasone and systemic effects?

A

Inhaled drug is 90% swallowed; fluticasone normally has very high first pass metabolism but if this is inhibited e.g. protease inhibitors then can get systemic toxicity.

42
Q

Management for specifically exercise-induced asthma?

A

ICS, SABA before exercise, and add LTRA/LABA/theophylline.

43
Q

What defines acute severe asthma?

A

PEF 33-50%, RR>24, HR>109, inability to COMPLETE SENTENCES. Can be treated in GP/ED; admit if persists after therapy.

44
Q

What defines moderate asthma?

A

Increasing symptoms, PEF 5-75% predicted. Treat at home or community.

45
Q

Life-threatening asthma features?

A

PEF <33%, sats <92% or <8kPa, NORMAL OR RAISED CO2, silent chest, cyanosis, feeble resp. effort, bradycardia/arrhythmia, hypotension, exhaustion, confusion, coma. May need ICU

46
Q

Near-fatal asthma?

A

Raised PaCO2 and/or requiring mechanical ventilation.

47
Q

Acute asthma management?

A

Give 02 if hypoxaemic (aim for (94-98%), SABA (MDI for acute severe, neb [O2 driven] for life-threatening; can do continuous neb if severe), steroids (oral pred or IV/IM hydrocortisone). If poor response to BD, can give nebulised SAMA along with SABA. IV B2 agonist can be given if inhaled not reliable.
If still bad, need senior review, and consider single dose IV MgSo4 as bridge to ITU or IV aminophylline in life-threatening. Neb MgSO4 NOT recommended.
Follow up: should be on pred for >5 days.

48
Q

Who gets admitted in acute asthma?

A

Any features of life-threatening or near fatal, any features of severe persisting after treatment. If PEF <75% predicted after an hour can be discharged.

49
Q

Who needs ITU in acute asthma?

A

Need ventilatory support, or acute severe/life-threatening who is failing to respond to therapy (falling PEF, persisting or deteriorating hypoxia, hypercapnia, ABG showing falling pH, exhaustion, drowsiness, resp. arrest.

50
Q

Asthma in paeds?

A

Use very low dose ICS. At stage 2 (i.e. when would normally add LABA), give LABA if over 5 and LTRA if under 5. Then proceed as before. Do not use LAMA at all, and do not use theophylline in stage 3 (can use in 4).

51
Q

Discharging after acute asthma?

A

Should have been on discharge meds for 12-24 hours, inhaler technique checked, PEFR >75% best, given oral and inhaled steroids, own PEFR meter and written asthma plan with GP follow up.

52
Q

COPD treatment protocol?

A

Give SAMA or SABA PRN.

  1. If still bad, and FEV1<50/60%, give LABA/ICS combination, or LAMA (stop SAMA).
  2. If FEV1 >50/60%, give LABA or LAMA (stop SAMA).
  3. If just given LABA, then give LABA and ICS if needed.
  4. All go from here to triple therapy!
53
Q

Other drugs in COPD?

A

If cannot use inhaler, or persisting SOB, can give oral theophylline. Can give mucolytic if have chronic productive cough. Can give LTOT if O2 <7.3 or <8 with polycythaemia/ankle swelling/PAH. Then give diuretics too. There is a role for prophylactic azithromycin.

54
Q

Oxygen management in acute COPD?

A
  1. If not peri-arrest, but at risk of T2RF, then target sats 88-92% and do ABG. Use 24%/28% O2; reduce if >92%.
  2. Get ABG; if PCO2 normal/low carry on. Repeat ABG in 30-60 mins.
  3. If pH normal but CO2 high, treat with lowest dose venturi mask that will maintain sats 88-92 and repeat ABG in 30-60 min.
  4. If pH <7.35 and PCO2 >6, consider NIV (BIPAP) and consider ITU.
55
Q

Management of IE of COPD?

A
  1. Do aminophylline level if on it. Follow O2 guidance (if hypoxic), assess NIV.
  2. Give BD (SABA or SAMA) (consider neb). Give nebs driven with compressed air if acidotic or hypercapnic.
  3. Oral antibiotics if purulent sputum (doxycycline, amoxicillin, macrolide)
  4. Oral prednisolone (30mg OD), no longer than 14 days.
  5. Intubation/NIV/ICU.
  6. IV theophylline if poor response to BD.
56
Q

Steroids in acute asthma?

A

ALL PATIENTS should get oral pred OD for >5 days.

CSIM2 (21 decks)

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