'Nil by Mouth' Medication Dose Calculators and Guidelines

There are two medication calculators in use by doctors, nurses and pharmacists who are looking after patients with Parkinson's who have been admitted to hospital and are unable to take their medications orally.

This page provides information on both calculators - healthcare staff should follow local guidelines on which to use. Calculators should be used consistently between prescribing staff working with the same patients. 

Last reviewed
Topic
  • Inpatient care and medicines management
Resource type
  • Tools
Profession
  • Doctor (Geriatrician)
  • Doctor (Neurologist)
  • Doctor (Other)
  • Nurse (other)
  • Nurse (Parkinson's nurse)
  • Pharmacist

READ BEFORE USE

Two medication calculators are currently in use by healthcare staff for patients with Parkinson's who are unable to take their medications orally. 

The two calculators can give different dosage conversions. Calculators should be used consistently between prescribing staff working with the same patients. Always refer to local guidance from your Parkinson's service on which calculator to use before prescribing. 

The two calculators are:

  • PD 'Nil by Mouth' Medication Dose Calculator (pdmedcalc.co.uk)
  • OPTIMAL Parkinson's calculator and guideline (parkinsonscalculator.com)

There is information about, and are links to, both calculators below. 

Parkinson's services are encouraged to document which calculator is recommended for use with their patients and to make this documentation readily available for non-specialist staff.

Parkinson's UK is not affiliated with either calculator. 

As of 2020, Parkinson's UK have not been able to confirm whether OPTIMAL has been reviewed or updated since 2018.

PD 'Nil by Mouth' Medication Dose Calculator (pdmedcalc.co.uk) 

Disclaimer

This tool is no substitute for clinical reasoning nor should it be used as a substitute for expert advice.

Extensive effort has been made to ensure this tool is as accurate as possible, however the accuracy and completeness of the information provided can not be guaranteed.

The tool should therefore be used as a guide, with no medical decision being solely made on the results provided by this tool.

Who is this tool for?

Doctors, nurses and pharmacists who are looking after patients with Parkinson's who have been admitted to hospital and are unable to take their medications orally.

What is the purpose of the tool?

In patients unable to take their usual Parkinson's medications orally, this tool is designed to convert a patient's usual Parkinson's medications to a 'Levodopa equivalent dose' (LED).

The LED can then be used to calculate what dose of dispersible madopar should be given via a nasogastric tube to provide a patient with their usual amount of Parkinson's medication.

The tool also provides a conversion to a rotigotine patch dose. A correction factor is applied to avoid large patch doses that may precipitate side effects such as confusion, hallucinations or delirium.

The following medications can be safely omitted if swallow is compromised: entacapone, selegiline, rasagiline and amantadine.

If the patient is on an Apomorphine infusion or uses Duodopa (via PEJ), then they do not need to be converted to a rotigotine patch – instead, please continue to use their existing non-oral treatment.

Where did this tool come from?

The tool was developed by the Northumbria Healthcare NHS Foundation Trust Parkinson's Disease team in 2014 (Richard Walker, Brian Wood, Annette Hand and James Fisher), who worked in collaboration with Daniel Jamieson (PhD student at Newcastle University's School of Computing Science).

Note for people affected by Parkinson's

This resource is intended for use by professionals only. People affected by Parkinson's are advised to consult with their specialists before making any changes to their medication.

OPTIMAL Parkinson's calculator and guideline (parkinsonscalculator.com)

What is the purpose of the tool?

The OPTIMAL guideline and calculator aims to help non-specialist clinical staff to better manage patients with Parkinson's when they are admitted to hospital in an emergency, better plan for elective admissions and direct staff to sources of specialist support.

Who is this tool for?

The guideline and conversion calculator is for non-specialist clinical staff who need to manage their patient's Parkinson's medication until support is available from their local Parkinson's specialist or pharmacist.

It is not intended to replace locally-agreed guidelines and prescribing practices, but rather offer guidance until specialist advice can be obtained.

Where did this tool come from?

The guideline and calculator have been developed by a team of Parkinson's specialists and pharmacists, with the support of the Wessex Parkinson's Excellence Network and the British Geriatrics Society Movement Disorders Section. The principal developers are:

Dr Gayle Strike, Consultant Geriatrician, University Hospital Southampton NHS Foundation Trust
Dr Naomi Fox, Consultant Geriatrician, Poole Hospital NHS Foundation Trust
Mr James Allen, Senior Pharmacist, University Hospital Southampton NHS Foundation Trust
Mr Ben Fox, Software Engineer

Note for people affected by Parkinson's

This resource is intended for use by professionals only. People affected by Parkinson's are advised to consult with their specialists before making any changes to their medication.

Disclaimer: as of 2020, Parkinson's UK have not been able to confirm whether OPTIMAL has been reviewed or updated since 2018.