NHS Greater Glasgow & Clyde Area Drug and Therapeutics Committee
Greater Glasgow and Clyde Medicines
Medicines Update Primary Care

Postscript Primary Care - February 2012

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Levothyroxine - Teva Brand

The MHRA have suspended the marketing authorisation for levothyroxine 100mcg tablets manufactured by Teva.  This follows a review by the Commission on Human Medicines (CHM) which concluded that the Teva product might not be interchangeable with other levothyroxine products.

Prescribers should be alert that a change in a patient’s symptoms and TSH status may be attributed to switching between the Teva product and another product.

Most patients are unlikely to notice any difference but patients who experience a significant change in symptoms should have their TSH status reviewed and their dose of levothyroxine adjusted accordingly.

The following patients may require particularly close monitoring:
• Pregnant women, throughout pregnancy but especially in the first trimester. (Pregnant women with thyroid disease are monitored routinely through the antenatal period by specialist services)
• Those with heart disease. (Specialists have intimated that the risk is low. GPs should be vigilant for patients with heart disease showing symptoms which suggest suboptimal treatment and investigate appropriately)
• Those under treatment with TSH suppressive doses of levothyroxine after treatment for thyroid cancer
These patients should be contacted and, if they are taking Teva tablets, be given an early appointment for a clinical review and blood test. After dose adjustment, TSH should be retested after a period of 6 weeks to confirm blood levels are stabilised within their normal range. Community pharmacies and hospitals have now withdrawn the affected products and are using other brands. For more information see: www.mhra.gov.uk/home/groups/comms-po/documents/news/con143690.pdf

Gabapentin and Pregabalin - Potential for misuse

Gabapentin and Pregabalin are licensed for the treatment of epilepsy and neuropathic pain. Pregabalin is also licensed for use in general anxiety disorder. Recently there have been reports of the potential for misuse of these drugs in order to enhance mood level, to augment the effects of other drugs, to manage opiate withdrawals and cravings or to substitute other drugs such as cocaine. Gabapentin and pregabalin are structurally related to the neurotransmitter GABA and it is this common role for GABA-related effects which is believed to cause the potential for these drugs to be misused by patients.

Although some studies focus on people misusing gabapentin with a history of cocaine dependence, anecdotal reports from certain Health Boards across Scotland have highlighted gabapentin misuse by opiate users. While the current evidence around gabapentin and pregabalin misuse is limited, both pharmacists and prescribers should be aware of the potential for misuse of these drugs and be cautious when prescribing either drug, particularly to individuals with a known history of substance misuse.

NRT Products - Contract Change

A new three year contract has been agreed within NHSGGC for the formulary preferred choice of nicotine replacement therapy (NRT).  From 5th March 2012, the NiQuitin® CQ patches will become the NRT formulation of choice, replacing Nicorette®.  Second line products are the NiQuitin® gum and lozenges which may be used for dual therapy also.

The change in provider will have significant benefits for the health board financially and in additional support to community pharmacies and patient support material. All other aspects of the NHSGGC Primary Care Smoking Cessation Guidance remain unchanged.

Dalteparin Prescribing

We have been made aware of a prescribing error in general practice for Dalteparin injection.  On EMIS these injections appear as below. This listing format means that careful selection of the correct product is required because the total number of units is listed after the units/ml.  In the Vision and GPASS systems, only the total units are included in the title.  Prescribers should take care to ensure that the correct product is selected.

 

Dermatology Prescribing

An approved list of specials that are accepted as unlicensed topical products commonly used within primary care in NHSGGC was endorsed by NHSGGC Dermatology Formulary Review Group on 19th January 2012.  This list will be available on the prescribing website shortly. Prescribing of unlicensed specially manufactured dermatology preparations is common.  Below is some advice for prescribers:
 
1. When choosing an ointment base yellow soft paraffin is preferred. 
 
2. Never prescribe a dilution of a topical steroid preparation that needs to be manufactured - all required potencies can be met from the existing commercial preparations.  The only potential exception to this would be the dilution of Diprosone® with Diprobase® where the manufacturer allows this dilution.
Specially manufactured mixtures are unlicensed and both the stability and potency of these mixtures is unknown. 
 
4. Never mix a coal tar, ichthammol or salicylic acid preparation with a steroid preparation (again due to stability issues and potential unknown effects on the potency of the steroid caused by the change in pH).  If for use together they need to be prescribed separately and applied as two preparations.

5. Coal tar or salicylic acid preparations should be prescribed as standard concentrations as included in the approved list (eg 1%, 2%, 5%, 10%, 15% and 20%).

Domperidone

McNeil® Products have recently written to prescribers advising of new information regarding cardiovascular risks of domperidone products.  They advise that studies have shown that domperidone may be associated with an increased risk of serious arrhythmias or sudden cardiac death.  They note the risk is highest in those on daily doses over 30mg or in people over 60 years. They advise domperidone should be avoided in patients taking other drugs known to prolong the QT interval.  Prescribers should be cautious using domperidone in patients with known QT prolongation, patients with electrolyte disturbance and those with underlying cardiac diseases such as congestive heart failure.

Hypertension Guidelines

The Heart MCN is reviewing and updating the local Hypertension Guidelines, these are expected to be submitted to the Area Drugs and Therapeutics Committee in April. This follows the publication of new NICE guidelines in England and Wales. Until this review is complete, prescribers should continue to follow the existing NHSGGC Hypertension Guideline.