Prescription drug sales in the United States grew substantially in 2003, supported by an upswing in new drug approvals and double-digit growth in many of the top-volume drug categories.
Sales grew by 11.5% to $217.4 billion in wholesale dollarsdespite inroads by generic drugs in such categories as hypertension, diabetes treatment, and antidepressantsas leading brands lost patent protection. Generic usage reached a record level and claimed 43% of total scripts dispensed, according to IMS Health, the prescription drug information company.
The year saw the approval of 21 new molecular entities (NMEs), compared with 2002, when only 17 NMEs came to market. The 2002 number had been the lowest since 1983.
Merck/Schering-Plough's Zetia (ezetimibe) and AstraZeneca's Crestor (rosuvastatin calcium), available since September, joined the group of lipid-lowering drugs, which remained the top-selling class, with 10.9% wholesale-dollar growth. Zetia, a cholesterol-absorption inhibitor, now ranks 148 in total retail and mail-order scripts dispensed (Tables 1 and 2).
Most patients using Zetia and Crestor were newly started on cholesterol-lowering therapy, according to IMS Health. Thus the impact of the new competition on Pfizer's Lipitor (atorvastatin calcium) and Merck's Zocor (simvastatin) was mitigated. Those 2 drugs maintained their leader status in the expanding category.
Eli Lilly and Company's new attention deficit/hyperactivity disorder (AD/HD) drug Strattera (atomoxetine hydrochloride) rapidly gained market share in AD/HD drugs and joined the rankings at 115 in wholesale sales to all channels (including hospitals, longterm care facilities, and clinics).
New specialty drug entries included Genentech/Novartis' subcutaneous asthma drug Xolair (omalizumab) and Raptiva (efalizumab), a plaque psoriasis drug by Genentech/Xoma. Also, Bayer's Levitra (vardenafil) and Lilly's Cialis (tadalafil) debuted to challenge Pfizer's Viagra (sildenafil citrate) in the erectile-dysfunction segment, each relying on heavy consumer marketing. Direct-to-consumer advertising overall played a larger role last year, helping new entries as well as established brandssuch as Pfizer's Zyrtec (cetirizine hydrochloride), AstraZeneca's Nexium (esomeprazole magnesium), and Schering's Clarinex (desloratadine)to grab market share.
Antihypertensive brands were the hardest hit by generics. Four angiotensin-converting enzyme inhibitors, Pfizer's Accupril (quinapril), Bristol-Myers Squibb's Monopril (fosinopril sodium), and the brand versions of lisinoprilMerck's Prinivil and Zeneca's Zestrillost patent and dropped in the script and dollar-sales rankings.
Along with the generic availability in the category, new mid-year guidelines by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, which favor diuretics in first-line treatment, impacted sales of antihypertensives.
Antihypertensive calcium channel blockers as a category declined by 5% in dollar sales, according to IMS. Pfizer's Norvasc (amlodipine besylate), however, remains a widely used brand, ranking 4 in total scripts dispensed.
Generic vendors captured share in diabetes drugs with the patent expirations of Bristol-Myers Squibb's Glucophage XR (metformin hydrochloride) and Pfizer's Glucotrol XL (glipizide). As those brands lost scripts and sales, metformin hydrochloride, offered by vendors including Par Pharmaceutical and IVAX, and glipizide, with generic entries from Andrx and Watson Labs, moved up.
Strong contenders such as Pfizer's Zoloft (sertraline hydrochloride) and Forest Labs' Celexa (citalopram hydrobromide) contributed to an 11.9% increase in dollars in the antidepressant category, according to IMS Health. GlaxoSmithKline minimized loss of market share by converting patients from Paxil (paroxetine) to Paxil CR. The reformulated molecule climbed to 72 in total scripts. Also in the depression category, Organon's patent-losing drug Remeron (mirtazapine) lost position, as generic companies including Akzo Nobel, Teva Pharmaceutical, Barr Labs, Mylan Labs, and Roxane lined up with low-cost alternatives.
As sales in the categories of heartburn and hay fever relief were challenged last year by generic and OTC availability, continuing strength of prescription brands in both segments is noteworthy. Boosted by the reported epidemic of obesity and unhealthy eating habits, proton pump inhibitors grew 12.9% in dollar sales. Tap Pharm's Prevacid (lansoprazole) and AstraZeneca's Nexium achieved doubledigit sales growth. Wyeth's Protonix (pantoprazole sodium) and Eisai/Janssen's Aciphex (rabeprazole sodium) placed in the top 40 in dollar sales, despite inroads by omeprazole, supplied by 3 generic companies.
The switch of Schering's Claritin (loratadine) affected Rx antihistamines, which nose-dived by 28% in sales in 2003. Yet, leading brands, notably Pfizer's Zyrtec and Aventis' Allegra (fexofenadine hydrochloride), held up quite well despite a full-year of OTC loratadine availability. Brands' efficacy often varies by patient, so drugs are less likely to be deemed as interchangeable in the category.
Mr. Vaczek is a freelance medical writer based in Yonkers, NY.
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