Regorafenib (Stivarga – Bayer), a multikinase inhibitor, has been approved by the FDA for treatment of patients with metastatic colorectal cancer previously treated with multiple other regimens specified in the labeling. It has also been approved for use in treatment-refractory, locally advanced, unresectable or metastatic gastrointestinal stromal tumor (GIST).

Atorvastatin (Lipitor - Parke-Davis), an HMG-CoA reductase inhibitor (or 'statin'), was recently approved by the US Food and Drug Administration for treatment of primary hypercholesterolemia and mixed dyslipidemia. A single stereoisomer of a pyrrole derivative, the new drug is chemically different from other statins.

Aliskiren (Tekturna - Novartis), the first direct renin inhibitor for treatment of hypertension, has been approved for use in a fixed-dose combination with the diuretic hydrochlorothiazide (Tekturna HCT - Novartis). Many angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are also available in fixed-dose combinations with hydrochlorothiazide (HCTZ).

A recent letter to the editor of the Annals of Internal Medicine documented a single case of myopathy apparently due to an interaction between simvastatin (Zocor, and others) and green tea. Since it became available generically, simvastatin has surpassed atorvastatin (Lipitor) as the best selling statin. As such, it is probably the most common cause of statin-induced myopathy, which is often a result of drug interactions.

The labeling of dabigatran etexilate (Pradaxa – Boehringer Ingelheim), an oral direct thrombin inhibitor, has recently been updated to include new dosing and monitoring recommendations and a warning on the risk of bleeding. Dabigatran etexilate was approved in the US in 2010 for the prevention of thromboembolic stroke in patients with non-valvular atrial fibrillation. It has been shown to be more effective than warfarin (Coumadin, and others) for this indication.

Tolterodine tartrate (Detrol - Pharmacia & Upjohn) is a new muscarinic receptor antagonist now being widely promoted for treatment of urinary frequency, urgency and urge incontinence caused by bladder (detrusor) overactivity.

Changes caused by one drug in the absorption, distribution, metabolism or excretion of another may lead to a pharmacokinetic adverse drug interaction (DN Juurlink et al, JAMA 2003; 289:1652). Additive drug interactions, such as vasodilation caused by both sildenafil (Viagra) and nitrates, can also have adverse effects.

The FDA has approved Tekamlo (Novartis), an oral fixed-dose combination of the direct renin inhibitor aliskiren (Tekturna) and the calcium channel blocker amlodipine (Norvasc, and others), for treatment of hypertension in patients not adequately controlled on monotherapy or already taking both drugs, and as initial therapy in those likely to need multiple drugs to control their blood pressure (BP). Both aliskiren and amlodipine are available in combinations with other antihypertensive agents.

Calcipotriene ointment 0.005% (calcipotriol; Dovonex - Westwood Squibb), a synthetic vitamin D 3 analog previously available in Europe and Canada, has now been approved by the US Food and Drug Administration (FDA) for treatment of moderate plaque psoriasis, the most common form of the disease.

The FDA has approved a nasal spray formulation of fentanyl (Lazanda – Archimedes) for management of breakthrough pain in adult cancer patients who are already receiving and are tolerant to opioid therapy. Fentanyl is already available in the US for intravenous, intrathecal, epidural, transdermal and oral transmucosal use.