On 14 March, Corium announced that Adlarity (donepezil hydrochloride) had received FDA approval as a treatment for patients with mild, moderate or severe dementia of Alzheimer’s disease (AD). Adlarity is the first and only once-weekly transdermal patch that delivers stable doses of donepezil. This route of administration reduces the likelihood of the adverse gastrointestinal (GI) side effects that are often associated with oral donepezil. But because Adlarity is the fourth cholinesterase inhibitor product to launch in the US market, it is entering a fiercely competitive space for the symptomatic treatment of AD.

Donepezil is the most commonly prescribed medication in a class of AD drugs known as the cholinesterase inhibitors and is considered to be the gold standard symptomatic treatment for AD. Adlarity’s uptake is expected to be moderate, as it will be the first transdermal patch formulation of donepezil available in the US. The patch will be available in two dose formulations: 5mg a day or 10mg a day. Treatment consists of a single patch that can be placed by the patient or caregiver on a patient’s back, thigh or buttocks. Its once-weekly application will set it apart from other cholinesterase products with more frequent daily oral or transdermal dosing. This is not only ideal for patients who have difficulty swallowing tablets, but the dosing schedule will also help with compliance and reduce the caregiver’s burden. GlobalData forecasts Adlarity to reach sales of $203m by 2030.

In addition to competing with Aricept and generic versions of oral donepezil, which dominate the market, Adlarity is also expected to face tough competition from other marketed cholinesterase inhibitors, many of which have also experienced generic erosion and are likely to have lower annual costs when compared to Adlarity. Rivastigmine, branded as Exelon, is a non-specific cholinesterase inhibitor that is also available in multiple doses and as both once-daily oral and transdermal formulations to fit a range of patient lifestyles, preferences, and needs. Galantamine, branded as Razadyne, is a reversible inhibitor of acetylcholinesterase but also enhances the intrinsic action of acetylcholine on nicotinic receptors. Through this dual mechanism of action, the drug increases cholinergic neurotransmission in the central nervous system. Furthermore, Namzaric (donepezil + memantine XR) is the first combination therapy to be approved for moderate to severe AD. The memantine component of the drug may potentiate the effect of cholinesterase inhibitors. According to GlobalData, the cholinesterase inhibitors combined are forecast to contribute $895.9m to the US AD market by 2030.

Cholinesterase inhibitors, however, only provide symptomatic relief and do not treat the underlying cause of AD. Although disease-modifying therapies are still in early days, the potential remains in the future for the use of combination treatment regimens pairing cholinesterase inhibitors with disease-modifying products. This type of regimen may be made even more feasible for patients due to the availability of a once-weekly donepezil product like Adlarity.