In the US, price inflation for the most widely-used branded drugs during the year to September 2012 was more than six times greater than overall economic price inflation for consumer goods, according to new data.

The price gap between brand-name and generic medicines widened by an additional 35.2% percentage points from September 2011 to September 2012, according to the report, from US pharmacy benefit manager (PBM) Express Scripts, which adds that this is the largest one-year increase it has recorded since it started publishing its annual Drug Trend Report back in 1997.

Prices on a market basket of the most highly-utilised brand-name medications increased 13.3% in the 12 months to September 2012, far outpacing the overall economic inflation level of 2%, while prices of generic drugs declined 21.9% during the same period, says the report, which combines   for the first timedata from Express Scripts and the PBM Medco, which was acquired by Express Scripts earlier this year.

During the first three-quarters of 2012, US spending on traditional medications decreased 0.6% compared to the same period in 2011, driven primarily by lower prices brought on by increased use of generics, says the report.

It also finds the top traditional therapy class during the year to be mental and neurological disorders, including antidepressants. This class now consumes 24.7% of all US spending on traditional drugs, and while use of these treatments has increased 3.1% compared to the first three quarters of 2011, total expenditure in the class is down 1.9%, as a result of the recent availability of generic antidepressants and antipsychotics.

Also, total US spending on medications to treat high blood pressure and high cholesterol decreased 7.7% during the year to September, primarily driven by the continued impact of patent expiries on blockbuster treatments.

Spending on specialty drugs continues to rise by double-digit rates year on year, the report finds. During the first three-quarters of 2012, such expenditures increased 22.6% over the same period of 2011, driven primarily by unit cost increases and, in the first nine months of 2012, specialty drug costs consumed 20.8% of total pharmacy spend.

The three therapy classes representing the largest amount of US specialty drug spend continue to be rheumatoid arthritis/autoimmune conditions, multiple sclerosis and cancer, while the largest specialty trend increase is reported for commonly-used treatments for hepatitis C, rising 117.3% over the period. Increased utilisation is driving this latter trend, as new patients begin and continue treatment with one of two new medications.

Eight of the nine notable new medications approved by the US Food and Drug Administration (FDA) during the third quarter were specialty medications, and many of these are second- and third-line drugs indicated for the treatment of advanced cancers, the study points out.

It also reviews the two new anti-obesity medications approved this summer by the FDA - Belviq (lorcaserin), which is manufactured by Swiss drugmaker Arena Pharmaceuticals and distributed in the US by Eisai, and Vivus' Qsymia (phentermine and topiramate extended-release). In clinical trials, many patients taking either of these new treatments lost at least 5% of their body weight.