Proton pump inhibitors may be the only commercially significant group of drugs to gain "pharmacologic class" status in the revisions to U.S. Pharmacopeia's model guidelines for Medicare drug plans.

USP presented its ¹ final model guidelines to the Centers for Medicare & Medicaid Services Dec. 31 and, although there have been modifications from the August draft, they retain the same number of unique therapeutic categories and pharmacologic classes - 146 - as originally proposed (² Also see "USP Draft Medicare Formulary Sets 146 Drug Categories And Classes" - Pink Sheet, 23 August, 2004., p. 5).

The draft guidelines listed PPIs as a "recommended subdivision" of an "antiulcer agents" class within the "gastrointestinal agents" category. Under the Medicare Modernization Act and the draft Medicare Part D implementing regs, the formulary "safe harbor" and the two-drug coverage requirement apply only to drug categories and classes.

All three of the former antiulcer subdivisions - PPIs, H2 blockers and protectants - are considered distinct classes in the final guidelines.

PPIs include AstraZeneca's Nexium , Wyeth's Protonix , Johnson & Johnson/Eisai's Aciphex and TAP's Prevacid , as well as omeprazole (AstraZeneca's Prilosec and generics).

Another class addition in the GI category is irritable bowel syndrome agents. In exchange, antidiarrheal agents, laxatives and promotility agents were dropped as classes.

Overall, the numbers in USP's final guidelines changed only slightly.

The final guidelines contain 41 therapeutic categories, 32 with associated pharmacologic classes and nine with no classes listed; the proposed model included 43 therapeutic categories, 35 of which contained separate classes. The final draft sets out 137 pharmacologic classes, whereas the initial version included 138.

Adding the 137 classes to the nine categories with no associated classes produces the 146 total unique drug groupings.

In addition to meeting basic category and class design requirements, CMS outlined in draft formulary review guidelines how it intends to review drug lists for their medical appropriateness (³ Also see "Medicare Formulary Guide Looks Beyond USP For Principles On Rx Classes" - Pink Sheet, 13 December, 2004., p. 19).

To provide input into the CMS review process, USP removed its "recommended subdivisions" from the model guidelines and submitted them instead as "formulary key drug types" in comments on the CMS document (see ⁴ Also see "USP “Key Drug Types” Could Serve As CMS Standard For Medicare Rx Plans" - Pink Sheet, 10 January, 2005.).

USP wants CMS to flag formularies that do not include at least one drug in each of the 118 "key drug types." As a result, some pharmacologic classes might have to include more than two drugs to ensure an expeditious review.

Overall, compliance with that approach would mean covering at least 336 different drugs (not accounting for drugs that could be placed in multiple groups). That total calls for 12 fewer drugs than would have been necessary under USP's initial formulary guidelines (⁵ Also see "USP Drug Classification System Suggests At Least 348 Drugs On Formularies" - Pink Sheet, 6 September, 2004., p. 17).

The pharmaceutical industry and potential Medicare Rx plan sponsors have been at odds over revisions to the USP document. The drug industry has sought a larger number of categories that would call for coverage of more products, while health plans have advocated more flexible guidelines.

USP's final product suggests the organization declined to substantially alter its position amid stakeholders' conflicting pressure.

Attempts by individual manufacturers to secure a distinct class for one of their products in the model guidelines generally did not pan out.

Sanofi-Aventis had a minor success in gaining recognition of ketolide antibiotics as one of the key drug types; the company's Ketek is the only ketolide antibiotic approved.

A researcher associated with Sanofi-Aventis urged USP to classify ketolides as a pharmacologic class, but their addition to the supplemental list could be sufficient to foster formulary placement. (⁶ Also see "Ketek, Allegra Deserve Special Formulary Status – Aventis Consultants" - Pink Sheet, 6 September, 2004., p. 25).

Several other groups of blockbuster drugs are not specifically represented on the final USP model. SSRI and SNRI antidepressants, for instance, remain listed as "key drug types," just as they were placed in recommended subdivisions in the initial draft.

The beleaguered group of COX-2 inhibitors also remains in the supplemental column, off of the formal USP model. In the final guidelines, COX-2s have been switched from the "anti-inflammatories" category to "analgesics."

Safety concerns about COX-2s surfaced while USP was revising its formulary guidelines, but the organization said those issues are not the reason for the move.

Statins also remain a "key drug type" in the final version; they were classified as a "recommended subdivision" in the proposed model (⁷ Also see "COX-2s, Statins Have No Class In USP Medicare Draft Formulary" - Pink Sheet, 23 August, 2004., p. 3).

Allergy drugs are placed in a broader class under USP's final classification than in the draft.

The H1 blocker allergy drugs - including Schering-Plough's Clarinex , Sanofi-Aventis' Allegra and Pfizer's Zyrtec - were originally listed as their own class within an "antihistamine" therapeutic category, which has been removed in the final guidelines.

Antihistamines are now listed as a single class in the "respiratory tract agents" category. The class is divided into two key drug types: "mildly/non-sedating" and "sedating" H1 blocking agents.

In the draft, H1 blockers were subdivided into "sedating" and "non-sedating" groups. Sanofi-Aventis asked USP to divide the drugs into sedating, mildly sedating and non-sedating groups, but health plans opposed treating H1 blockers with such specificity. Plans also argued they should only be required to offer one drug in classes with OTC options.

Overall, six therapeutic categories in the initial proposal have been deleted, turned into a class or otherwise revised in the final model: antidotes, deterrents and poison control; antihistamines; antipsoriatics; antipyretics; memory enhancers - dementia; and nasal and throat agents.

The final draft model guidelines include three new categories: inflammatory bowel disease agents, antidementia, deterrents/replacements and toxicologic agents.

USP Final Formulary Guide Adds PPI Class, But Has Few Other Changes

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