Videx EC (ddI, didanosine) – food restrictions

Formulation

Videx EC is a different formulation to Videx chewable / dispersible tablets and as such demonstrates a different absorption pattern.

Named Patient Supply

On the 17th April 2000, Bristol-Myers Squibb, commenced the supply of Videx EC on a named patient basis. At that time, data about timing of administration in relation to food was only available for the existing licensed formulation of Videx chewable tablets. In the written guidance provided to healthcare professionals it was recommended that Videx EC capsules were taken “30 minutes before food and 2 hours after food”, consistent with the licence for the existing Videx tablet formulation. Under the conditions of the named patient provision of any drug, the drug is not licensed and so, whilst the company provide guidance on the its use, responsibility for administration of the drug lies with the prescribing physician.

Videx EC licence

Further pharmacokinetic data, including food interaction studies, was submitted to the European regulatory authorities in order to obtain a licence for Videx EC in the UK and other EU countries. The licence was reviewed under the mutual recognition procedure. As part of this procedure all European member states review the submission documents simultaneously. During this review process, one member state raised a query about pre-food dosing of Videx EC and requested that Bristol-Myers Squibb conduct further food interaction studies. This data will further establish the recommended dosing of Videx EC capsules before food.

Videx EC Dosing Recommendations

It is recommended that Videx EC be taken 2 hours after food1. Until further studies have been completed and recommendations established, a precise recommendation for the timing of Videx EC administration prior to eating cannot be made. It is therefore suggested that Videx EC be taken 2 hours after food, a convenient time being before bedtime.

Comment

Enteric coated ddI is a different formulation to the buffered versions and therefore has its own PK and bioavailibility profile. Discovering that food interactions post- dosing may require an extended fasting period this late in the development process was not expected. The company are now unable to recommend a safe post dose fasting period until the results from this study are analysed.

As these new indictations are very different from those previously provided to patients, clinics should contact patients already enrolled in studies or on the named-patient programme to advise them of the change to pre-dose fasting requirements.As a precautionary measure prior to exact post-dose fasting requirements being known it may be advisable to recommend a similar 2 hour period after dosing before food is taken.

The suggestion to move dosing to last thing at night,rather than first thing in the morning,will provide the greatest change to daily regimens for most patients.

It has also become clear that patients are still not being provided with correct dosing information when prescibed the currently licenced formulations.

It is well established that the ‘reduced-mass’ 200mg and original 100mg formulations require a fasting period before and after dosing – ‘BOTH 30 minutes before food AND 2 hours after food’. While manufacturers are not responsible for information that pharmacies include on the label as patient information, many clinics have been advising ’30 minutes before food OR 2 hours after food’ on the medicine labels.

Ensuring clear information is always provided to patient labels is particularly important given that doctors and patients have been expecting that the EC formulation would lead to a less restrictive dietary schedule.