Top 100 Drugs Flashcards
Give 1 example of a 5-alpha-reductase inhibitor
Finasteride
Give 1 common indication for a 5-alpha-reductase inhibitor
Benign Prostatic Hyperplasia
Give the mechanism of action for a 5-alpha-reductase inhibitor
Inhibit 5-alpha-reductase, which prevents the conversion of testosterone to it’s more active form - dihydrotestosterone which normally stimulates prostatic growth. Inhibiting this enzyme causes the prostate to shrink, reducing bulk of the gland and reducing obstruction to the outflow of urine.
What are the common side effects of 5-alpha-reductase inhibitors?
Relate to anti-androgen action: gynaecomastia, impotence, reduced libido.
Give 1 caution for 5-alpha-reductase use
Exposure to the male fetus can cause malformation of the external genitalia. The drug may not be prepared or handled by anyone who could be pregnant. The drug is also passed via semen, so caution should be used in those having unprotected sex with those who could be pregnant.
Give 2 examples of alpha blockers
- Doxazosin
- Tamsulosin
Give 2 common indications for alpha blockers
- BPH
- Resistant hypertension
Give the mechanism of action for alpha blockers
Antagonise alpha-1-adrenoreceptors, which are found in smooth muscle (including blood vessels and the urinary tract), causing relaxation. They therefore cause vasodilation and a subsequent fall in blood pressure, and reduced resistance to bladder outflow.
What are the common side effects of alpha blockers?
Relate to their effect on vascular tone: postural hypotension, dizziness, syncope.
Give 1 caution for alpha blocker use
Existing postural hypotension.
Give 1 interaction for alpha blocker use
Beta blockers - they prevent the reflex tachycardia that forms part of the compensatory response to the vasodilation caused by alpha blockers.
What time of day should alpha blockers be administered?
Bedtime - due to pronounced BP lowering effect and the associated risk of dizziness, syncope and falls.
Give 2 examples of acetylcholinesterase inhibitors
- Donepezil
- Rivastigmine
Give 2 common indications for acetylcholinesterase inhibitors
- Alzheimer’s disease
- Dementia in Parkinson’s disease.
Give the mechanism of action for acetylcholinesterase inhibitors
ACh is an important neurotransmitter for cognition and memory, a decrease in which is seen in Alzheimer’s disease and dementia associated with Parkinson’s disease. These drugs inhibit the acetylcholinesterase enzyme, preventing the breakdown of ACh and increasing it’s availability for neurotransmission. They therefore decrease the rate of cognitive decline.
What are the common side effects of acetylcholinesterase inhibitors?
Relating to increased peripheral cholinergic activity: nausea, vomiting, diarrhoea.
Relating to increased central cholinergic activity: hallucinations, altered behaviour, extra-pyramidal side effects, neuroleptic malignant syndrome.
Exacerbation of asthma and COPD.
Peptic ulcers, bradycardia, heart block.
Give 4 cautions for acetylcholinesterase inhibitors
- Asthma and COPD
- Peptic ulcer disease
- Heart block
- Parkinson’s disease - rivastigmine may worsen tremor
Give 2 indications for n-acetylcysteine
- Paracetamol overdose
- To reduce the viscosity of respiratory secretions (as a mucolytic)
Give the mechanism of action of n-acetylcysteine
Paracetamol metabolism normally produces a small amount of the hepatotoxic substance NAPQI, which is detoxified by conjugation with glutathione. In paracetamol overdose the body’s supply of glutathione is overwhelmed, and so n-acetylcysteine aims to replenish the body’s supply of glutathione and prevent hepatic damage.
Breaks disulphide bonds in mucus, reducing it’s viscosity.
What are the common side effects of n-acetylcysteine?
Anaphylactoid reaction - similar to anaphylaxis but involves histamine release independent of IgE, so once symptoms have settled (with help of antihistamine and bronchodilator) acetylcysteine therapy may be recommenced at a lower rate of infusion.
May cause bronchospasm when given nebulised (as a mucolytic).
Give 1 indication for activated charcoal
To reduce absorption of certain poisons (including some drugs in overdose) from the gut.
Give the mechanism of action of activated charcoal
Molecules are adsorbed onto the surface of the charcoal by Van der Waals forces, reducing their absorption into the circulation. Weakly ionic and hydrophobic substances are generally well adsorbed to activated charcoal.
Give 2 drugs which are well adsorbed by activated charcoal, and 4 which are not
Well adsorbed:
1. Benzodiazepines
2. Methotrexate
Poorly adsorbed:
1. Strong acids/bases
2. Alcohol
3. Iron
4. Lithium
What are the common side effects of activated charcoal?
Intestinal obstruction, black stools, vomiting.
Aspiration, leading to:
1. Bronchospasm
2. Pneumonitis
3. Airway obstruction
Give 3 cautions for activated charcoal use
- Reduced consciousness (unless ET tube in place as may result in aspiration)
- Persistent vomiting (due to risk of aspiration)
- Reduced gut motility (due to risk of intestinal obstruction)
Give 1 indication for adenosine
First-line diagnostic and therapeutic agent for rapid reversion to sinus rhythm in paroxysmal supra-ventricular tachycardia.
Give the mechanism of action of adenosine
Activates adenosine receptors on cell surfaces in the heart, resulting in reduced frequency of spontaneous depolarisation (automaticity) and increasing resistance to depolarisation (refractoriness). This slows sinus rate and conduction velocity, and increases AV node refractoriness.
Many forms of SVT result from a self-perpetuating re-entry circuit in the AV node. Increased refractoriness in the AV node breaks the re-entry circuit, allowing the normal depolarisations of the SA node to re-take control over heart rate.
Has a half-life of roughly 10 seconds.
What are the common side effects of adenosine?
Interferes with function of SA and AV nodes, and so can induce bradycardia and asystole.
Breathlessness and bronchospasm.
Can cause deeply unpleasant feeling in the chest, described as a ‘sinking feeling’ or ‘sense of impending doom’.
Give 5 cautions for adenosine use
Those who could not tolerate it’s transient bradycardic effects:
1. Hypotension
2. Coronary ischaemia
3. Decompensated heart failure
Those who could not tolerate bronchospasm:
4. Asthma
5. COPD
Give 3 indications for adrenaline
- Cardiac arrest
- Anaphylaxis
- Local vasoconstriction, e.g. to control mucosal bleeding in endoscopy and prolong local anaesthesia
Give the mechanism of action for adrenaline
Potent a1, a2, B1 and B2 adrenoreceptor agonist, therefore having multiple sympathetic effects:
1. Vasoconstriction of vessels supplying the skin, mucosa and abdominal viscera (mainly a1 mediated)
2. Increased force of contraction, myocardial excitability and heart rate (mainly B1 mediated)
3. Vasodilation of vessels supplying the heart and muscles (mainly B2 mediated)
These therefore cause redistribution of blood flow in favour of the heart, bronchodilation and suppression of inflammatory mediator release.
What are the common side effects of adrenaline?
- Adrenaline-induced hypertension
- Anxiety
- Tremor
- Headache
- Palpitations
- MI/angina/arrhythmias
Give 1 caution for adrenaline use
- Do not use in areas with poor vascularisation (e.g. fingers and toes) due to risk of tissue necrosis.
Give 2 examples of aldosterone antagonists
- Spironolactone
- Eplerenone
Give 3 common indications for aldosterone antagonist use
- Ascites and oedema due to liver cirrhosis
- Chronic heart failure
- Primary hyperaldosteronism
Give the mechanism of action for aldosterone antagonists
Aldosterone is a mineralocorticoid which normally acts on the distal tubules of the nephron to increase the activity of luminal epithelial sodium channels (ENaC) - subsequently increasing sodium and water retention and elevating blood pressure, with associated increased potassium excretion.
Aldosterone antagonists competitively inhibit the aldosterone receptors to increase sodium and water excretion, as well as potassium retention.
What are the common side effects of aldosterone antagonists?
- Hyperkalaemia (weakness, arrhythmia, cardiac arrest)
- Gynaecomastia (spironolactone)
- Liver impairment and jaundice
- Stevens-Johnson syndrome
Give 4 cautions to aldosterone antagonist use
- Hyperkalaemia
- Severe renal impairment
- Addison’s disease (those who are aldosterone deficient)
- Pregnant or lactating women (can cross placenta and are expressed in breast milk)
Name 3 important drug interactions for aldosterone antagonists
- ACE-inhibitors
- ARBs
- Potassium supplements
All of these drugs can also elevate potassium
Give 2 examples of alginates and antacids
- Gaviscon
- Peptac
Give 2 common indications of alginate and antacid use
- GORD (for symptomatic relief)
- Dyspepsia
Give the mechanism of action for alginates and antacids
Antacids: buffer stomach acids
Alginates: increase the viscosity of stomach contents, reducing reflux into the oesophagus. Form a floating ‘raft’ to separate the gastric contents from the gastro-oesophageal junction to prevent mucosal damage.
Give 2 side effects of alginate and antacids
- Constipation (aluminium salts)
- Diarrhoea (magnesium salts)
Give 2 cautions to alginate and antacid use
- Thickened milk preparations in infants - can lead to excessively thick stomach contents.
- Renal failure - sodium and potassium containing compounds should be used with caution
Give 6 drug interactions for alginates and antacids
Can bind to other drugs and reduce serum concentrations, so doses should be separated by 2 hours.
- PPIs
- Digoxin
- ACE inhibitors
- Antibiotics (ciprofloxacin, cephalosporins, tetracycline)
- Bisphosphonates
- Levothyroxine
Give 3 indications for allopurinol use
- Gout
- Prevention of uric acid and calcium oxalate renal stones
- Prevention of hyperuricaemia and tumour lysis syndrome in chemotherapy
Give the mechanism of action for allopurinol
Xanthine oxidase inhibitor.
Xanthine oxidase metabolises xanthine (produced from purines) to uric acid, so inhibiting this enzyme reduces plasma uric acid concentrations and subsequent deposition in joints and kidneys.
Give 5 side effects of allopurinol use
- Triggering/worsening of acute attack of gout (risk of triggering acute attack may be reduced by co-prescription of NSAID or colchicine)
- Skin rash
- Stevens-Johnson Syndrome
- Toxic epidermal necrolysis
- Allopurinol hypersensitivity syndrome (rare, life-threatening reaction to allopurinol characterised by fever, eosinophilia, lymphadenopathy)
Give 4 cautions to allopurinol use
- Acute attacks of gout
- Severe hypersensitivity
- Hepatic impairment (metabolised by liver)
- Renal impairment (excreted by kidney)
Give 2 drug interactions for allopurinol
- Azathioprine - it’s active metabolite is metabolised by xanthine oxidase
- ACE inhibitors - co-prescription increases the risk of hypersensitivity
Give 3 examples of aminoglycosides
- Gentamicin
- Neomycin
- Amikacin
Give 5 indications for aminoglycoside use
- Severe sepsis
- Pyelonephritis and complicated UTIs
- Biliary and intra-abdominal sepsis
- Endocarditis
- Bacterial skin/eye/external ear infections (topical preparations)
Give the spectrum of activity of aminoglycosides
Gram-negative aerobic bacteria
Inactive against streptococci and anaerobes, so should be co-prescribed with penicillin or metronidazole when the causative organism is unknown.
Give the mechanism of action of aminoglycosides
Bind irreversibly to bacterial ribosomes to inhibit protein synthesis - bactericidal.
Enter cells via an oxygen-dependent mechanism, and so are ineffective against anaerobes and streptococci (which do not have this mechanism).
Give 2 side effects of aminoglycoside use
- Nephrotoxicity - accumulate in renal tubular epithelial cells
- Ototoxicity - accumulate in cochlear and vestibular hair cells
Give 4 cautions to aminoglycoside use
- Renal impairment - as renally excreted
- Neonates
- Elderly
- Myasthenia gravis - can impair neuromuscular transmission
Give 3 important drug interactions of aminoglycosides
- Loop diuretics (increased risk of ototoxicity)
- Vancomycin (increased risk of ototoxicity and nephrotoxicity)
- Cephalosporins (increased risk of nephrotoxicity)
Give 2 examples of aminosalicylates
- Mesalazine
- Sulfasalazine
Give 2 indications of aminosalicylate use
- Ulcerative colitis (mesalazine)
- Rheumatoid arthritis (sulfasalazine)
Give the mechanism of action of aminosalicylates
Release 5-aminosalicylic acid (5-ASA), which has anti-inflammatory and immunosuppressive effects. Acts topically in the gut rather than systemically.
Give 6 side effects of aminosalicylate use
- GI upset
- Headache
- Blood abnormalities (leucopenia, thrombocytopenia)
- Renal impairment
- Oligospermia
- Hypersensitivity
Give 1 caution to aminosalicylate use
- Aspirin sensitivity - aspirin is also a salicylate
Give 2 drug interactions for aminosalicylates
- PPIs - mesalazine has a pH sensitive coating, and so drugs which alter gastric pH may cause the coating to breakdown prematurely.
- Lactulose - alters stool pH and may prevent 5-ASA release in the colon.
Give 1 indication for amiodarone use
- Tachyarrhythmias (e.g. AF, atrial flutter, SVT, VT and VF) - where other therapeutic options (drugs or electrical cardioversion) are ineffective or inappropriate
Give the mechanism of action of amiodarone
Blockade of sodium, potassium and calcium channels in myocardial cells.
Antagonism of alpha and beta adrenergic receptors.
These effects reduce spontaneous depolarisation (automaticity), slow conduction velocity and increase resistance to depolarisation (refractoriness).
Give 5 side effects of amiodarone use
- Hypotension
- Pneumonitis
- Bradycardia and AV block
- Hepatitis
- Thyroid abnormality
Give 3 cautions for amiodarone use
- Hypotension
- Heart block
- Active thyroid disease
Give 3 drug interactions for amiodarone
Increases plasma concentrations of:
- Digoxin
- Diltiazem
- Verapamil
Give 3 examples of ACE inhibitor
- Ramipril
- Lisinopril
- Perindopril
Give 4 indications for ACE inhibitor use
- Hypertension - 1st/2nd line
- CHF - 1st line
- IHD
- Diabetic nephropathy and CKD with proteinuria
Give the mechanism of action of ACE inhibitors
Block angiotensin converting enzyme to prevent the conversion of angiotensin I to angiotensin II.
Angiotensin II is a vasoconstrictor and stimulates aldosterone secretion. Blocking it’s action reduces peripheral vascular resistance to lower BP.
Dilates the efferent glomerular arteriole to reduce intraglomerular pressure and reduce progression of CKD.
Reducing aldosterone secretion promotes sodium and water excretion, reducing venous return (preload) and having a beneficial effect on BP and in HF.
Give 6 side effects of ACE inhibitor use
- Persistent dry cough
- Hypotension
- Renal failure
- Hyperkalaemia
- Angioedema
- Anaphylactoid reaction
Give 3 cautions to ACE inhibitor use
- Renal artery stenosis
- AKI
- Pregnancy and breastfeeding
Give 2 drug interactions for ACE inhibitors
- Potassium elevating drugs (including potassium supplements)
- NSAIDs - when co-prescribed there is an increased risk of nephrotoxicity
Give 2 examples of ARBs
- Candesartan
- Losartan
Give 4 indications for ARB use
- Hypertension - 1st/2nd line
- CHF - 1st line
- IHD
- Diabetic nephropathy and CKD with proteinuria
Give the mechanism of action of ARBs
Angiotensin receptor blockers.
Block the action of angiotensin II on the angiotensin receptors, resulting in vasodilation and reduced aldosterone secretion.
Give 3 side effects of ARB use
- Hypotension
- Renal failure
- Hyperkalaemia
Give 3 cautions to ARB use
- Renal artery stenosis
- AKI
- Pregnancy and breastfeeding
Give 2 drug interactions of ARBs
- Potassium elevating drugs (including potassium supplements)
- NSAIDs - when co-prescribed there is an increased risk of nephrotoxicity
Give 4 examples of SSRI
- Fluoxetine
- Citalopram
- Sertraline
- Escitalopram
Give 3 indications for SSRI use
- Moderate to severe depression
- Panic disorder
- OCD
Give the mechanism of action for SSRIs
Selective serotonin reuptake inhibitors.
Inhibit neuronal reuptake of serotonin from the synaptic cleft to increase availability for neurotransmission.
Give 7 side effects of SSRIs
- GI upset
- Changes in appetite and weight loss
- Suicidal ideation
- Serotonin syndrome
- Hyponatraemia
- Lowered seizure threshold
- Prolonged QT interval
Give 4 cautions for SSRI use
- Epilepsy
- Peptic ulcer disease
- Young people - have poor efficacy and have associated increased risk of self harm and suicidal thoughts
- Hepatic impairment - SSRIs are metabolised by the liver
Give 3 drug interactions for SSRIs
- Monoamine oxidase inhibitors - seretonergic
- Tramadol - seretonergic
- Antipsychotics - prolong the QT interval
Give 1 example of a tricyclic antidepressant
- Amitriptyline
Give 2 indications for tricyclic antidepressants
- Moderate to severe depression
- Neuropathic pain
Give the mechanism of action for tricyclic antidepressants
Inhibit neuronal reuptake of serotonin and noradrenaline from the synaptic cleft, making more available for neurotransmission.
Also have effect on many receptors (e.g. muscarinic, H1, D2 and a1/a2) which accounts for large array of side effects.
Give 8 side effects of tricyclic antidepressant use
- Dry mouth/constipation/urinary retention/blurred vision - due to antimuscarinic effects
- Sedation and hypotension - due to blockade oh H1 and a1 receptors
- Arrhythmias
- Convulsions
- Hallucinations
- Mania
- Sexual dysfunction
- Extrapyramidal side effects - tremor and dyskinesia
Give 6 cautions to tricyclic antidepressant use
- Epilepsy
- Elderly
- CVD
- Prostatic hypertrophy (due to antimuscarinic effect)
- Glaucoma
- Constipation
Give 1 drug interaction for tricyclic antidepressants
- Monoamine oxidase inhibitors - both drugs increase serotonin and noradrenaline levels at the synapse
Give 2 indications for venlafaxine and mirtazapine use
- Major depression - 2nd line where SSRIs are ineffective
- Generalised anxiety disorder (venlafaxine)
Give the mechanism of action of venlafaxine
Serotonin and noradrenaline reuptake inhibitor (SNRI), increasing availability for neurotransmission.
Weaker antagonist of muscarinic and H1 receptors than tricyclic antidepressants, so cause fewer antimuscarinic side effects.
Give the mechanism of action of mirtazapine
Antagonist of inhibitory pre-synaptic a2-adrenoreceptors, increasing availability of monoamines for neurotransmission.
Potent H1 antagonist, but weaker antagonist of muscarinic receptors - have fewer antimuscarinic side effects than tricyclic antidepressants but frequently cause sedation.
Give 5 side effects of venlafaxine and mirtazapine use
- GI upset
- Serotonin syndrome
- Hyponatraemia
- Suicidal thoughts
- Neurological effects (e.g. headache, abnormal dreams, insomnia, confusion, convulsions)
Give 4 cautions for venlafaxine and mirtazapine use
- Elderly
- Arrhythmias
- Hepatic impairment
- Renal impairment
Give 2 examples of D2-receptor antagonists
- Metoclopramide
- Domperidone
Give 1 indication for D2-receptor antagonist use
- Nausea and vomiting - particularly in reduced gut motility
Give the mechanism of action of D2-receptor antagonists
D2-receptor is the main chemoreceptor in the chemoreceptor-trigger zole (CTZ) - the area responsible for sensing emetogenic substances in the blood and transmitting it to the vomiting centre in the medulla.
D2 is a neurotransmitter in the gut, promoting relaxation of the gut and lower oesophageal sphincter. Antagonising D2 receptors has a prokinetic effect - promoting gastric emptying and contributing to their effect in N+V due to reduced gut motility (e.g. due to opioids).
Give 5 side effects of D2-receptor antagonist use
- Diarrhoea
- Extrapyramidal syndromes - metoclopramide only, as domperidone does not cross the blood-brain barrier
- Acute dystonic reaction - involuntary muscle contractions (e.g. oculogyric crisis - spasmodic movements of the eyeballs into a fixed position)
- Prolonged QI interval
- Arrhythmias
Give 5 cautions for D2-receptor antagonist use
- Parkinson’s disease (only metoclopramide - domperidone does not cross the blood-brain barrier)
- Neonates
- Hepatic impairment (domperidone)
- Intestinal obstruction/perforation - due to prokinetic effects
- Cardiac conduction abnormalities (domperidone)
Give 4 drug interactions for D2-receptor antagonists
- Dopaminergic agents for Parkinson’s - metoclopramide as it antagonises their effects
- Antipsychotics - metoclopramide only due to risk of extra-pyramidal side effects
- Drugs which prolong the QT interval (e.g. antipsychotics, quinine, SSRIs)
- Cytochrome P450 inhibitors (e.g. amiodarone, diltiazem, macrolides, fluconazole, protease inhibitors)
Give 3 examples of antiemetic H1-receptor antagonists
- Cinnarizine
- Cyclizine
- Promethazine
Give 1 indication for antiemetic H1-receptor antagonist use
- Nausea and vomiting - particularly in motion sickness or vertigo
Give the mechanism of action of antiemetic H1-receptor antagonists
H1 and ACh (muscarinic) receptors predominate the vomiting centre in the medulla, and in it’s communication with the vestibular system.
Blocking these receptors prevents the sensation of nausea and subsequent vomiting - particularly in motion sickness and vertigo due to the vestibular effect.
Give 4 side effects of antiemetic H1-receptor antagonists
- Drowsiness
- Dry throat and mouth - due to anticholinergic effects
- Tachycardia
- Palpitations
Give 2 cautions to antiemetic H1-receptor antagonist use
- Hepatic encephalopathy - due to sedating effect
- Prostatic enlargement - due to risk of urinary retention as a result of antimuscarinic effects.
Give 2 drug interactions for antiemetic H1-receptor antagonists
- Other sedative medications, e.g. benzodiazepines, opioids
- Antimuscarinics, e.g. ipratropium, tiotropium
Give 2 examples of 5-HT3-receptor antagonists
- Ondansetron
- Granisetron
Give 1 indication for 5-HT3-receptor antagonists
- Nausea and vomiting - particularly in general anaesthesia and chemotherapy
Give the mechanism of action of 5-HT3-receptor antagonists
High density of 5-HT3-receptors in the chemoreceptor trigger zone (CTZ), and 5-HT3 is the key neurotransmitter released by the gut in response to emetogenic stimuli. Therefore blockade of these receptors prevents vomiting.
5-HT3 is not involved in communication with the vestibular system, and so these drugs are not useful in N+V due to motion sickness or vertigo.
Give 1 caution for 5-HT3-receptor antagonist use
- Prolonged QT interval - as these medications can also have this effect.
Give 3 drug interactions for 5-HT3-receptor antagonists
Drugs which prolong the QT interval:
1. Quinine
2. SSRIs
3. Antipsychotics
Give 3 examples of anti-fungal drugs
- Fluconazole
- Clotrimazole
- Nystatin
Give 2 indications for anti-fungal drug use
- Local fungal infection - including oropharynx, vagina and skin
- Systemic fungal infection
Give the mechanism of action of anti-fungal drugs
Fungal cell membranes contain ergosterol, which is not seen in animal or human cells.
Nystatin (polyene antifungal) binds to ergosterol to create a polar pore, allowing ions to leak from the cell and resulting in death or slowed growth of the fungus.
Fluconazole (triazole antifungal) and clotrimazole (imidazole antifungal) inhibit ergosterol synthesis, subsequently impairing cell growth and replication.
Give 3 side effects of anti-fungal drugs
- Local irritation
- GI upset for those taken orally
- Hepatitis and severe hepatic toxicity
Give 4 examples of antihistamine H1-receptor antagonists
- Cetirizine
- Loratadine
- Fexofenadine
- Chlorphenamine
Give 3 indications for antihistamine H1-receptor antagonist use
- Allergies (particularly hayfever - seasonal allergic rhinitis)
- Prutitus and urticaria
- Anaphylaxis (as an adjunct after administration of life-saving medications)
Give the mechanism of action of antihistamine H1-receptor antagonists
Histamine is released from mast cells as a result of IgE binding.
Histamine induces the features of type 1 (immediate) hypersensitivity (oedema, erythema, irritation, urticaria and itch).
Antagonising the H1 receptor blocks these actions of excess histamine.
Give 1 side effect of antihistamine H1-receptor antagonists
- Sedation - as H1 has a role in the brain in maintaining wakefulness. Newer ‘second-generation’ antihistamines (e.g. loratadine, cetirizine, fexofenadine) do not cross the blood-brain barrier and so do not cause sedation.
Give 1 caution to antihistamine H1-receptor antagonist use
- Severe liver disease - may precipitate hepatic encephalopathy
Give 1 example of an anti-motility drug
- Loperamide
Give 1 indication for anti-motility drug use
- Diarrhoea
Give the mechanism of action for anti-motility drugs
Loperamide is an opioid which does not cross the blood-brain barrier, but still has gastrointestinal effects.
It is an agonist of the opioid receptors in the gut, reducing peristaltic contractions and slowing the passage of bowel contents. This facilitates more time for water absorption, resulting in hardening of stool.
Give 1 side effect of anti-motility drug use
- GI upset - constipation, abdominal cramping, flatulence
Give 3 cautions for anti-motility drug use
- Acute ulcerative colitis - inhibition of peristalsis may increase the risk of megacolon and perforation
- C. diff infection
- Acute bloody diarrhoea (dysentery)
Give 2 examples of antimuscarinic bronchodilators
- Tiotropium
- Ipratropium
Give 2 indications for antimuscarinic bronchodilator use
- COPD
- Asthma (short acting for fast relief alongside SABA, or long acting for maintenance alongside LABA and corticosteroid)
Give the mechanism of action for antimuscarinic bronchodilators
Bind to the muscarinic receptor, where they act as a competitive inhibitor of ACh.
Stimulation of ACh receptors causes parasympathetic effects.
Inhibition of ACh causes sympathetic effects: increased heart rate, reduced smooth muscle tone (including respiratory tract and bladder), reduced secretions (including tears, respiratory and GI tract), pupillary dilation.
Give 2 side effects of antimuscarinic bronchodilator use
- Respiratory tract irritation
- GI upset - dry mouth and constipation
Give 3 cautions to antimuscarinic bronchodilator use
Due to antimuscarinic sympathetic effects - although in practice most patients can take these drugs inhaled without any significant effects, due to the drugs being quickly hydrolysed once they enter the circulation.
- Angle-closure glaucoma
- Arrhythmias
- Urinary retention
Give 1 example of a cardiovascular antimuscarinic
- Atropine
Give 1 indication for cardiovascular antimuscarinic use
- Bradycardia
Give the mechanism of action for cardiovascular antimuscarinics
Competitively inhibit muscarinic (ACh) receptors, resulting in sympathetic effects - such as increased heart rate.
Give 4 side effects of cardiovascular antimuscarinic use
- Tachycardia
- Dry mouth
- Constipation
- Urinary retention
Give 3 cautions to cardiovascular antimuscarinic use
- Angle-closure glaucoma
- Arrhythmias
- Urinary retention
Give 1 example of a gastrointestinal antimuscarinic
- Hyoscine butylbromide (buscopan)
Give 1 indication for gastrointestinal antimuscarinic use
- Irritable bowel syndrome
Also used to reduce secretions in palliative care
Give the mechanism of action for gastrointestinal antimuscarinics
Competitively inhibit muscarinic ACh receptors, resulting in sympathetic effects such as reduced smooth muscle tone and reduced secretions.
Give 4 side effects of gastrointestinal antimuscarinic use
- Tachycardia
- Dry mouth
- Constipation
- Urinary retention