These problems are exacerbated in elderly patients, who are more likely to be taking multiple medications. It is estimated that £800 million worth of drugs is wasted annually in primary care. A report from a group of people drawn from academia, medicine and patient groups suggests this could increase further with a reduction in patient adherence due to Automatic Generic Substitution. Under Automatic Generic Substitution, a patient could receive a different medication, with a different appearance and dosage instructions, on each visit to the pharmacy. There are many cases where generic prescribing is fully appropriate and vital to containing costs. Generic prescribing in the UK is currently at 83%. The Association of the British Pharmaceutical Industry (ABPI) suggests that the maximum possible level for generic prescribing would be in the region of 90%, as a number of medicines have either no generic equivalent or are not appropriate for substitution, e.g. slow-release formulations. Prescribers now commonly prescribe a generic over a brand-name product in cases where it does not present any significant disadvantages to their patients. The DH is proposing three options for introducing generic substitution:  The DH favours Option 3; Introduction of dispensing flexibility but limiting the scheme in such a way that the arrangements only apply to a selected group of products on a select list  The initial inclusion list for Option 3 can be found here  If Option 3 is adopted, the list can be "revised" by DH without any further consultation and may be revised up to four times per year. A group of people drawn from academia, medicine and patient groups has raised concerns in a report, ‘Automatic Generic Substitution – Clinical Implications for Patients’ that any substitution could be detrimental to the patient. It is known that many medicines have the potential to interact with each other. Medicines on the inclusion list could be substituted for a different version and interact differently with a patient’s established medicine. This could be a particular issue for the elderly, who often have multiple conditions and receive multiple medications. A study of patients registered with 201 UK general practices showed that patients aged 65–69 years received repeat prescriptions for an average of 5.9 medications in 2005.