About 50% of national Medicare drug plans have increased the amount enrollees pay for brand-name drugs.

Analysts at the Henry J. Kaiser Family Foundation, Menlo Park, Calif., report that finding in a review of the Medicare drug plan market.

Since 2006, average cost-sharing for a 30-day supply of “non-preferred” brand-name drugs in Medicare Part D prescription drug plans has increased by 29%, to $71.31, while average cost-sharing for “preferred” brand drugs has increased by 11%, to $29.86. Cost sharing for generic drugs has remained fairly stable since 2006, the analysts report.

Specialty tiers are commonly used by stand-alone Medicare prescription drug plans for relatively expensive drugs – those that cost at least $600 per month – and plans are able to charge more for specialty-tier drugs than they typically do for preferred or non-preferred drugs.

For 2008, 41 of the 47 nationally available Medicare drug plans will place some drugs in a specialty tier. That’s about twice the number of plans that had a specialty tier in 2006, according to the Kaiser analysts.