Merck's Singulair approval in allergic rhinitis presents a challenge for managed care to differentiate between the drug's existing asthma indication and its use in allergies when making coverage decisions.

With a number of managed care companies requiring prior authorization for prescription antihistamines in light of over-the-counter Claritin , Singulair could have an advantage over other prescription allergic rhinitis drugs since it is already widely covered for asthma.

FDA approved Singulair (montelukast) Dec. 31 for "the relief of symptoms of seasonal allergic rhinitis in adults and pediatric patients 2 years of age and older." The drug was approved for asthma in 1998 and is now indicated for children 12 months and older.

Merck recently suggested to investors that managed care may not be able to determine the specific indication for which Singulair is prescribed, and thus ultimately will cover its use in both asthma and allergies. Singulair is currently covered on 99% of managed care lives.

Human Health President-Americas David Anstice noted during Merck's annual business review that one tool managed care uses to distinguish between indications - dosing - is not applicable to Singulair because both its indications use the same dose.

Singulair's dosing schedule is slightly different between the two indications: for asthma, the drug should be taken once in the evening, while for allergy patients, administration can be tailored to suit individual needs, labeling says. Patients with both conditions should take one dose in the evening.

"Another way they could differentiate [between the two indications] is if there are other lead disease indicators," Anstice said. "You can often tell heart failure patients because of other concomitant therapies. That's not immediately obvious in this category."

"Since so many asthma patients also have concomitant allergic rhinitis, and so many allergy patients have asthma, then even if you [had] data, it wouldn't necessarily be conclusive as to what condition they're treating for," the exec noted. Merck estimates that as many as 40% of allergy sufferers also have asthma.

One managed care company, WellPoint, says it will be able to distinguish between Singulair scripts for allergic rhinitis and asthma by checking its patient database for concomitant beta agonist use.

Singulair's formulary placement will be discussed by WellPoint's Pharmacy & Therapeutics committee during the first quarter, but the company noted that it can implement draft recommendations before that time. Use of Singulair as allergy relief only is expected to require prior authorization.

Due to the Claritin switch, WellPoint will require prior authorization starting Jan. 31 for all Rx antihistamines - Schering-Plough's Clarinex (desloratadine), Pfizer's Zyrtec (cetirizine) and AstraZeneca's Allegra (fexofenadine). FDA cleared Schering's OTC Claritin Nov. 27 (¹ Also see "Schering OTC Claritin Will Launch In December Without Rx Transition Period" - Pink Sheet, 2 December, 2002., p. 7).

Like WellPoint, Cigna will also use its patient database to draw conclusions as to whether Singulair is being prescribed for asthma or allergic rhinitis. In addition to checking for concomitant asthma medications, the managed care company will reference patient histories for evidence of past treatment for asthma or allergies.

Singulair will go before Cigna's P&T committee in January, with a decision expected prior to start of the allergy season, the company said. Singulair is currently a second-tier product for asthma.

Cigna has remanded all Rx antihistamines to non-preferred, third-tier status, effective Jan. 1. Claritin and Allegra were previously second-tier products, while Zyrtec and Clarinex were considered third-tier, the company said.

Despite the availability of OTC loratadine Merck expects to grow Singulair in 2003. The company is forecasting a range of $2 bil. to $2.3 bil. in 2003 versus an expected $1.4 bil. to $1.6 bil. in 2002 (² Also see "Singulair Allergy Approval Will Drive Sales Despite OTC Claritin, Merck Says" - Pink Sheet, 9 December, 2002., p. 16).

To meet that goal, Merck will capitalize on Singulair's novel mechanism of action: a leukotriene-blocking activity that works across multiple allergic rhinitis symptoms (³ Also see "Singulair Advantage In Allergies Is Leukotriene-Blocking Action, Merck Says" - Pink Sheet, 16 December, 2002., p. 28).

By blocking leukotrienes, Singulair works on the sneezing and runny nose symptoms that occur during the early stage of allergic rhinitis, while also relieving congestion associated with the later stages, Merck said.

Revised Singulair labeling states that leukotrienes "are released from the nasal mucosa after allergen exposure during both early- and late-phase reactions and are associated with symptoms of allergic rhinitis." Leukotrienes have "been shown to increase nasal airway resistance and symptoms of nasal obstruction."

Singulair's novel mechanism of action will be highlighted by Merck in marketing efforts. The company has said it plans to treat the allergic rhinitis approval as a new launch, rather than a supplemental indication, and will promote the allergy indication with a sales team that is separate from the asthma reps.

Singulair allergic rhinitis efficacy was demonstrated in five trials enrolling a total of 5,029 patients, 1,799 of whom were treated with montelukast, labeling says. Four of the five trials showed a statistically significant difference in the nasal symptom scores versus placebo.

Labeling details the results of one trial, which shows a -.39-point mean change in nasal symptoms from baseline for Singulair 10 mg, on a 0-3 scale, compared to -.26 for placebo and -.46 for Claritin. The study was not designed to compare the two actives.

In Singulair patients 15 years and older, the most common adverse event was upper respiratory infection (1.9% montelukast vs. 1.5% placebo). In patients two to 14 years of age, events occurring in at least 2% of Singulair patients were headache, otitis media, pharyngitis and upper respiratory infection.

The Singulair label has also been updated with three additional adverse reactions in the post-marketing experience section: agitation including aggressive behavior, arthralgia and palpitations.

Merck filed the allergic rhinitis sNDAs in the first quarter of 2002; the company was expecting approval in early 2003. The three sNDA filings (20-829/S-017; 20-830/S-020; and 21-409/S-003) are for Singulair tablets, chewable tablets and oral granules.

Merck Singulair Presents Managed Care Test: Covering Asthma, Not Allergies

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