@reesprescribe.bsky.social
Associate Professor of Therapeutics and enthusiastic learner and teacher of all things medicines and prescribing. Author of the '7 days of a drug' series', which was previously on Twitter/X
Day 7: #ticagrelor is usually stopped after 12 months. The ‘dual anti-platelet therapy (DAPT)’ is justified when thrombosis risk is high in the post event period, but once risk drops, the bleeding risk outweighs the anti-thrombotic value. There are exceptions to this & individual assessment needed
December 10, 2025 at 3:44 PM
Day 7: #ticagrelor is usually stopped after 12 months. The ‘dual anti-platelet therapy (DAPT)’ is justified when thrombosis risk is high in the post event period, but once risk drops, the bleeding risk outweighs the anti-thrombotic value. There are exceptions to this & individual assessment needed
Day 6: Drug-drug interactions: synergistic effect with all antiplatelets, anti-coagulants & NSAIDs. Strong CYP3A4 inhibitors eg clarithromycin, keto/itraconazole, ritonavir can increase effects. CYP3A4 inducers e.g carbamazepine can lower (NOT exhaustive)
December 10, 2025 at 3:42 PM
Day 6: Drug-drug interactions: synergistic effect with all antiplatelets, anti-coagulants & NSAIDs. Strong CYP3A4 inhibitors eg clarithromycin, keto/itraconazole, ritonavir can increase effects. CYP3A4 inducers e.g carbamazepine can lower (NOT exhaustive)
Day 5 (cont): Reversal of #ticragelor in emergency is possible via new monoclonal antibody drug Bentracimab. This has been designed to reverse #ticagrelor bleeding and is currently awaiting NICE/NHS approval, as well as FDA review.
December 10, 2025 at 3:41 PM
Day 5 (cont): Reversal of #ticragelor in emergency is possible via new monoclonal antibody drug Bentracimab. This has been designed to reverse #ticagrelor bleeding and is currently awaiting NICE/NHS approval, as well as FDA review.
Day 5: ADEs: Common include bleeding, constipation, hyperuricaemia/gout, dizziness/syncope, hypotension, rash. Uncommon/rare: haemorrhage eg eye, intra-cranial, muscular, angioedema (NOT exhaustive). Avoid in pregnancy
December 10, 2025 at 3:39 PM
Day 5: ADEs: Common include bleeding, constipation, hyperuricaemia/gout, dizziness/syncope, hypotension, rash. Uncommon/rare: haemorrhage eg eye, intra-cranial, muscular, angioedema (NOT exhaustive). Avoid in pregnancy
Day 4: Mechanism of action #ticagrelor. It is a potent reversible platelet P2Y12 receptor antagonist. This receptor normally promotes platelet aggregation via ADP binding as part of haemostasis. Blocking this pathway inhibits platelet activation/aggregation, exerting an anti-thrombotic effect
December 10, 2025 at 3:38 PM
Day 4: Mechanism of action #ticagrelor. It is a potent reversible platelet P2Y12 receptor antagonist. This receptor normally promotes platelet aggregation via ADP binding as part of haemostasis. Blocking this pathway inhibits platelet activation/aggregation, exerting an anti-thrombotic effect
Day 3 (cont) #ticagrelor is a CYP3A4 & P-gp substrate & can itself cause inhibition of aforementioned processes. Some ethnic variation in response, for example, Asian populations may have higher bleeding risks
December 10, 2025 at 3:38 PM
Day 3 (cont) #ticagrelor is a CYP3A4 & P-gp substrate & can itself cause inhibition of aforementioned processes. Some ethnic variation in response, for example, Asian populations may have higher bleeding risks
Day 3: Rapid oral absorption/low bioavailability/fast onset of action. High Vd & plasma protein binding. Hepatic metabolism via CYP450 enzymes;active metabolite ~ 40% activity of parent compound. Excretion hepatic/biliary. Caution in hepatic impairment. T½ 7hrs parent compound & 8.5 hrs metabolite
December 10, 2025 at 3:36 PM
Day 3: Rapid oral absorption/low bioavailability/fast onset of action. High Vd & plasma protein binding. Hepatic metabolism via CYP450 enzymes;active metabolite ~ 40% activity of parent compound. Excretion hepatic/biliary. Caution in hepatic impairment. T½ 7hrs parent compound & 8.5 hrs metabolite
Day 2: Licensed for adults in combination with aspirin for prevention of events in acute coronary syndrome/post MI. Standard duration 12 mths; can continue for longer if nec. Unlicensed use for TIA/minor stroke when low bleeding risk. Dose dependent on indication, with loading dose for ACS
December 10, 2025 at 3:35 PM
Day 2: Licensed for adults in combination with aspirin for prevention of events in acute coronary syndrome/post MI. Standard duration 12 mths; can continue for longer if nec. Unlicensed use for TIA/minor stroke when low bleeding risk. Dose dependent on indication, with loading dose for ACS
Day 1: The limitations of prodrug clopidogrel drove development of alternative orally active P2Y12 inhibitors for anti-platelet therapy. In 2003, a structure was discovered based on ATP, an endogenous P2Y12 inhibitor. #ticagrelor was licensed EMA 2011
December 10, 2025 at 3:34 PM
Day 1: The limitations of prodrug clopidogrel drove development of alternative orally active P2Y12 inhibitors for anti-platelet therapy. In 2003, a structure was discovered based on ATP, an endogenous P2Y12 inhibitor. #ticagrelor was licensed EMA 2011
Day 7: In higher doses Pgp action can be saturated, allowing CNS entry of #loperamide with potential for euphoric effects/opioid issues. Abuse of loperamide linked to cardiovascular reactions eg syncope, rhythm disorders & rarely cardiac arrest. Abuse includes self-use to assist opioid withdrawal
November 16, 2025 at 4:18 PM
Day 7: In higher doses Pgp action can be saturated, allowing CNS entry of #loperamide with potential for euphoric effects/opioid issues. Abuse of loperamide linked to cardiovascular reactions eg syncope, rhythm disorders & rarely cardiac arrest. Abuse includes self-use to assist opioid withdrawal
Day 6: DDIs. Enzyme inhibition can lead to increased exposure to #loperamide & this can have a ‘severe’ warning & ‘caution advised’ eg dronedarone. Also, synergistic effect with other drugs which can produce constipation eg clozapine (NOT exhaustive)
November 16, 2025 at 4:17 PM
Day 6: DDIs. Enzyme inhibition can lead to increased exposure to #loperamide & this can have a ‘severe’ warning & ‘caution advised’ eg dronedarone. Also, synergistic effect with other drugs which can produce constipation eg clozapine (NOT exhaustive)
Day 5(cont): SPC states #loperamide can have a ‘moderate’ impact on driving ability. Although not a controlled drug, if relevant impairment is present, a drug driving offense may be committed
November 16, 2025 at 4:16 PM
Day 5(cont): SPC states #loperamide can have a ‘moderate’ impact on driving ability. Although not a controlled drug, if relevant impairment is present, a drug driving offense may be committed
Day 5: GI disorders are common ADEs for #loperamide & extension of MOA is constipation. However, abdo pain or vomiting are uncommon & paralytic ileus or megacolon are rare. Opioid-type issues are uncommon e.g dry mouth, or rare e.g impaired coordination, miosis, urinary retention(NOT exhaustive)
November 16, 2025 at 4:15 PM
Day 5: GI disorders are common ADEs for #loperamide & extension of MOA is constipation. However, abdo pain or vomiting are uncommon & paralytic ileus or megacolon are rare. Opioid-type issues are uncommon e.g dry mouth, or rare e.g impaired coordination, miosis, urinary retention(NOT exhaustive)
Day 4: #loperamide is a lipophilic synthetic opioid agonist which has a direct action on intestinal mu receptors. This slows peristalsis, retains water & electrolytes & increases rectal tone
November 14, 2025 at 8:09 PM
Day 4: #loperamide is a lipophilic synthetic opioid agonist which has a direct action on intestinal mu receptors. This slows peristalsis, retains water & electrolytes & increases rectal tone
Day 3 (cont) If hepatic impairment, there is reduced 1st pass/overall metabolism of #loperamide. Use with caution as may produce overdose effects. Also use with caution if history of opioid abuse. Avoid in pregnancy
November 14, 2025 at 8:09 PM
Day 3 (cont) If hepatic impairment, there is reduced 1st pass/overall metabolism of #loperamide. Use with caution as may produce overdose effects. Also use with caution if history of opioid abuse. Avoid in pregnancy
Day 3: #loperamide is absorbed/acts in the gut:onset action ~1hr. ↑ 1st pass metabolism minimises systemic bioavailability, as does being a PgP substrate. ↑plasma protein binding & Vd. Extensive hepatic metabolism via CY450 pathways > biliary then faecal excretion (no active metabolites). T½ ~11hrs
November 14, 2025 at 8:08 PM
Day 3: #loperamide is absorbed/acts in the gut:onset action ~1hr. ↑ 1st pass metabolism minimises systemic bioavailability, as does being a PgP substrate. ↑plasma protein binding & Vd. Extensive hepatic metabolism via CY450 pathways > biliary then faecal excretion (no active metabolites). T½ ~11hrs
Day 2 (cont): #loperamide also comes as combined with simeticone to calm colic & flatulence. As well as a POM, #loperamide can also be accessed over the counter in the UK
November 12, 2025 at 9:05 AM
Day 2 (cont): #loperamide also comes as combined with simeticone to calm colic & flatulence. As well as a POM, #loperamide can also be accessed over the counter in the UK
Day 2: Oral use (tabs,caps,melts)licensed for acute & chronic diarrhoea in adults (4-16mg/day divided) & for acute diarrhoea for those >4 (tabs:dose age dependent). Licensed for faecal incontinence & for palliative bowel colic pain & chemo-related diarrhoea; also symptoms of irritable bowel syndrome
November 12, 2025 at 9:03 AM
Day 2: Oral use (tabs,caps,melts)licensed for acute & chronic diarrhoea in adults (4-16mg/day divided) & for acute diarrhoea for those >4 (tabs:dose age dependent). Licensed for faecal incontinence & for palliative bowel colic pain & chemo-related diarrhoea; also symptoms of irritable bowel syndrome
Day 1: Invented in 1969, #loperamide was designed to be an active opioid compound in the peripheral nervous system, with low CNS effects. This allows slowed gut transition time, without psychoactive & addiction effects
November 12, 2025 at 9:02 AM
Day 1: Invented in 1969, #loperamide was designed to be an active opioid compound in the peripheral nervous system, with low CNS effects. This allows slowed gut transition time, without psychoactive & addiction effects
Day 7: #flecainide has a narrow therapeutic index & requires careful monitoring to avoid arrhythmias or cardiac arrest. Plasma concentration is monitored where there is an increased risk of toxicity eg renal or hepatic impairment, when high doses are needed, or when interacting drugs are used
October 17, 2025 at 5:38 PM
Day 7: #flecainide has a narrow therapeutic index & requires careful monitoring to avoid arrhythmias or cardiac arrest. Plasma concentration is monitored where there is an increased risk of toxicity eg renal or hepatic impairment, when high doses are needed, or when interacting drugs are used
Day 6: Some severe DDIs if #flecainide is combined with other anti-arrhythmic drugs e.g beta blockers, verapamil, amiodarone (if combined can reduce flecainide dose), or if used with enzyme inhibitors e.g ritonavir (NOT exhaustive)
October 17, 2025 at 5:37 PM
Day 6: Some severe DDIs if #flecainide is combined with other anti-arrhythmic drugs e.g beta blockers, verapamil, amiodarone (if combined can reduce flecainide dose), or if used with enzyme inhibitors e.g ritonavir (NOT exhaustive)
Day 5: Common ADRs are arrhythmias, dizziness, visual impairment, fatigue. Uncommon nausea & vomiting, GI disorders. Rare arthralgia, impotence, taste disorders (NOT exhaustive). #flecainide cannot be used if structural heart disease or cardiac failure
October 17, 2025 at 5:35 PM
Day 5: Common ADRs are arrhythmias, dizziness, visual impairment, fatigue. Uncommon nausea & vomiting, GI disorders. Rare arthralgia, impotence, taste disorders (NOT exhaustive). #flecainide cannot be used if structural heart disease or cardiac failure
Day 4 (cont) #flecainide blocks sodium channels in a rate dependent manner. This means that #flecainide binds preferentially to open channels, therefore the effect increases with the rapid activity seen in arrhythmias
October 17, 2025 at 5:32 PM
Day 4 (cont) #flecainide blocks sodium channels in a rate dependent manner. This means that #flecainide binds preferentially to open channels, therefore the effect increases with the rapid activity seen in arrhythmias