PD 'Nil by Mouth' Medication Dose Calculator

This medication calculator is for 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. The information in the tool should be read carefully before use.

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

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).


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.


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.

This is another available Parkinson's medication conversion calculator. It may produce different dosage conversions to the PD 'Nil By Mouth' Medication Dose Calculator. 

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.

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.

OPTIMAL is currently not listed in the Excellence Network resources directory as confirmation on updates is needed from the author. It can still be accessed on its own dedicated external site.