Greater Glasgow and Clyde Medicines

Key Messages

• Causes of QTc prolongation may be either inherited or acquired
• Drug induced QTc prolongation is the most common aetiology of acquired QTc prolongation
• Risk factors for QTc prolongation may be modifiable or non-modifiable
• Ensure that risk factors are reviewed and any modifiable risk factors such as electrolyte disturbance are corrected
• The concurrent use of more than one drug which prolongs the QTc interval increases the risk of Torsades de Pointes (TdP) and ventricular arrhythmia
• Some drugs which do not prolong the QTc interval themselves can increase the risk of QTc prolongation by affecting the metabolism of drugs which do
• Some drugs can increase the risk of QTc prolongation by causing electrolyte disturbances (in particular hypokalaemia, hypomagnesaemia and more rarely hypocalaemia) especially when given with QTc prolonging drugs
• Prescribers should ensure that the potential benefits of prescribing a QTc prolonging medication outweigh the associated risks, and that when a QTc prolonging medication is prescribed, appropriate mitigations and monitoring are in place

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• Anticholinergic drugs are associated with an increased risk of falls, confusion, and are linked to increased mortality in the older population (aged 65 years and older) 
• Adverse effects are cumulative and include constipation, urinary retention, postural hypotension, dizziness, and confusion 
• Review anticholinergic medications regularly to ensure treatment is still effective and the benefit outweighs the risk of harm

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Key Medicine Shortages October 2023 here

Includes:

Medicines for the treatment of attention deficit hyperactivity disorder (ADHD), Estradiol valerate/medroxyprogesterone acetate (Indivina®) 1mg/5mg tablets, Lixisenatide (Lyxumia®) 20micrograms/0.2ml solution for injection, Hyoscine hydrobromide (Scopoderm®) 1.5mg patches, Midazolam (Epistatus®) 2.5mg/0.25ml and 10mg/1ml oromucosal solution pre-filled oral syringes and products used in the treatment of scabies.

Key messages

• Do not withhold, omit or delay doses of medicines for MG (e.g. pyridostigmine or steroids) as there is a risk of myasthenic crisis if not administered on time.
• Where a patient does not have an individual supply of pyridostigmine this must be obtained urgently from pharmacy during working hours or via the local emergency cupboard, ward 67 at QEUH or the on call pharmacist if out of hours.
• Contact on call neurology registrar as soon as possible after admission (including out of hours) for patients with a history of MG that are experiencing MG related issues.
• Contact on call neurology routinely to inform them of admission for patients with a history of MG that are not experiencing any symptoms.
• High risk situations for patients with MG include: nil by mouth (NBM) status, infection and surgical procedures
• Some medicines can worsen or induce myasthenia gravis. Before prescribing any new medicines check the safety in the following guideline link

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MHRA Drug Safety Update September 2023 here

Access to the correct medications at the right time can be a problem for patients with PD when they are admitted to hospital.

Ensure medicines reconciliation is undertaken within 24 hours of admission – include the following: drug name, formulation, strength, dose and frequency. Exact dose timing of PD medications should be clearly annotated on HEPMA.

Key messages

• Prolongation of the QT interval can lead to a life threatening arrhythmia known as Torsades de Pointes (TdP)
• QT interval needs to be adjusted for heart rate, generating the widely used QTc (the corrected QT interval)
• There are several calculations available to correct the QT interval, with Bazett being the most widely used formula and the one used by many ECG machines to calculate the automated QTc. Bazett is however associated with significant limitations, which should be taken into account when interpreting the QTc reported on ECG printouts
• When reviewing a patients’ ECG, it is important not to look at the QTc interval in isolation to ensure that other conditions such as bradycardia, tachycardia, myocardial infarction or cardiomyopathy are not responsible for any changes in QTc

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Guideline News August 2023 here

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New NHSGGC guideline to help raise awareness and management of the interaction between oral tetracycline and fluoroquinolone antibiotics with multivalent cation-containing products (e.g. iron and calcium)

Key Medicine Shortages September 2023 here

Includes: Disulfiram, Jext (adrenaline), Phenytoin sodium, Pilocarpine hydrochloride, Minims® Povidone Iodine, Reboxetine (Edronax®), Tacrolimus (Adoport®), Tacrolimus (Dailiport®), Rifampicin 150mg/Isoniazid 75mg/Pyrazinamide 400mg/Ethambutol 275mg (Voractiv®), products used in the treatment of scabies: Permethrin 5% dermal cream (Lyclear®) and Malathion 0.5% liquid