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

PostScript Primary Care - Feb/March 13

To view this edition in PDF format click here

Short Supply of Medicines

We are aware that there are difficulties in the supply of some generic medicines (e.g. indapamide, isosorbide mononitrate and temazepam).

In some cases, it appears that where a particular product is temporarily unavailable, patients have been asked by community pharmacists to return to the prescriber to obtain a fresh prescription for a different strength or a branded equivalent. When products are recognised as being in short supply, specific arrangements are in place to help maintain continuity of supply to patients.

When medicines in short supply are officially recognised by Scottish Government and Community Pharmacy Scotland, community pharmacists have additional flexibility which may avoid the need to request a new prescription. For example, these allow community pharmacists to claim the cost of a branded product against a generic prescription. In addition, community pharmacists could substitute a different strength and alter the dose instructions and quantity e.g. 2 x 10 mg isosorbide mononitrate against a prescription for 20 mg isosorbide mononitrate. In cases where the drug formulation changes form conventional to sustained release; a new prescription will be required.

Community Pharmacists have been reminded of the actions that can be taken when dispensing a prescription for medicine on the short supply list.

The simplest source of information of regarding current short supply medicines is Community Pharmacy Scotland
(www.communitypharmacyscotland.org.uk).  On the right-hand side of the webpage is a link to current short supply medicines.   

Messages on shortages will also exist within ScriptSwitch® when feasible to advise GPs.

Isosorbide Mononitrate

Isosorbide mononitrate 10mg and 20mg standard release tablets are currently listed as short supply medicines. The Teva factory in South Wales that produces most of the UK supply has been temporarily closed down.  This problem is not shared by all community pharmacies; some have stock of 10mg and/or 20mg strengths. 

If there is no standard release isosorbide mononitrate available, a modified release (MR) preparation may be prescribed as a stop gap using an acute prescription while leaving the standard tablets on repeat for the future.   Stock levels are expects to recover in May / June.

The Department of Health have issued the following guidance:  ‘In the absence of normal release isosorbide mononitrate tablets being available, clinicians are advised to consider substitution with a slow release mononitrate preparation (which are not affected by this supply problem). Limited data exists regarding switching from normal release to modified release tablets but initially a mg per mg substitution would be appropriate (i.e. same daily dose overall) in most patients, and where available formulations allow.’  www.nelm.nhs.uk

In some cases where the formulations do not allow for dose for dose conversion the patient will require a dose increase, the reason for this is to prevent deterioration in angina control.  We have confirmed with cardiology services the doses of MR ISMN that can be switched from standard release tablets:

 Current dose of standard ISMN Suggested daily dose of ISMN MR 
 10mg twice daily  30mg daily
 20mg twice daily  60mg daily
 30mg twice daily  60mg daily
 40mg twice daily  90mg daily

Patients should be advised that they may experience a nitrate headache for a few days after conversion or potential drop in postural BP

All isosorbide mononitrate MR 60mg tablets are the same price if prescribed generically.  They are scored and can be halved.  There is likely to be high demand for MR products and they also may become in short supply. The community pharmacist may need to switch between brands which is acceptable, using the same daily dose.

Sertraline

Shortages of sertraline tablets are also being reported.  Some wholesalers have no stock at all and availability of both the generic and branded versions is patchy.  The suspension (50mg/5ml) is currently in stock according to the manufacturer.  Where a prescription cannot be filled because stock of all sertraline is exhausted it is recommended that an alternative SSRI antidepressant is considered.  The NHS GGC formulary first choice recommended SSRIs are citalopram and fluoxetine. 

Opinion of Mental Health clinicians is that citalopram would seem like the best option when the interaction profile and adverse effects are considered.  It is recognised that some people currently prescribed sertraline may have recently changed from citalopram because of concerns regarding QT interval prolongation.  QT interval prolongation and the co-prescribing of other medicines that prolong the QT interval needs to be considered when switching therapy.1  Fluoxetine could also be considered but there is a higher risk of interactions and potential issues with long-half life if switching back.

When switching to either citalopram or fluoxetine from sertraline closer monitoring is recommended.  In particular blood glucose monitoring with people with diabetes (particularly Type 1) and INR for people prescribed warfarin.2 

When switching from one SSRI to another their effects are so similar that administration of the second drug at the usual dose may not only be well tolerated, but may reduce discontinuation symptoms3. However, the abrupt switch between SSRIs may still produce discontinuation symptoms, and vigilance is still advised.  Maudsley also advises: taper and stop sertraline then start citalopram or fluoxetine at 10mg daily3.   

In order to reduce the risk of serotonin syndrome the starting dose of citalopram or fluoxetine is initially 10mg daily and increase to 20mg depending on response and side effects.

  1. Citalopram and escitalopram: QT interval prolongation www.mhra.gov.uk
  2. SSRI learning module: Important drug interactions www.mhra.gov.uk
  3. The Maudsley Prescribing Guidelines in Psychiatry 11th Edition 2012.

Calcipotriol with betamethasone (Dovobet®) Ointment

The manufacturer of Dovobet® are withdrawing the 60g ointment.  This will leave Dovobet® 120g ointment and 60g / 120g gel. 

Prescribers are reminded that:

  • Dovobet® is restricted to physicians experienced in treating inflammatory skin disease for use in patients who fail to comply with a twice daily regimen of the separate constituents.
  • Calcipotriol and betamethasone ointment or scalp preparation can be supplied individually at a significantly reduced cost.
  • A suggested regimen of the separate preparations may be calcipotriol applied in the morning and betamethasone applied at night.

Ointment

  • 120g of Dovobet® ointment costs £61.55
  • 120g of calcipotriol ointment plus 100g betamethasone diproprionate ointment costs £32.69 (£28.86 less expensive)

Scalp Preparations

  • Coal tar, salicylic acid and sulphur ointment is the Preferred List scalp preparation in NHSGGC
  • Dovobet® gel costs £61.43 for 120g and is a significantly hight cost product for the treatment of scalp psoriasis compared to the Preferred List product

Messages exist within ScriptSwitch® to support these Formulary recommendations.