In an oral formulation, acyclovir is not as bioavailable and even in a topical formulation applied directly to the site of the cold sore, according to Dr. Attali.
“The drug is released by the tablet for 12 to 15 hours, which covers the period where the virus is replicating,” Dr. Attali says. “If you look at the concentrations (of the drug) in saliva and mucosa, they are very high during that period. The use of this delivery system means that the lesion can abort. There are symptoms for one or two days, and then the lesion disappears.”
Indeed, acyclovir selectively inhibits HSV viral DNA replication, but systemic concentrations are reduced, delayed, and transient in the deep layers of mucosa and skin, thus poorly targeting the mucosal reservoir of HSV-1.
The amount of milk protein concentrate in the formulation is extremely low, so even patients with lactose intolerance can safely use this formulation. Younger patients can take it as well, Dr. Tyring says.
Apart from a significant advantage in terms of bioavailability, this formulation requires one application and eliminates the challenge of compliance that has existed with the oral formulation as well as the topical formulation of acyclovir, he says.
“There have been obstacles to overcome to ensure the optimal use of acyclovir and optimal healing,” Dr. Tyring says. “Compliance was always an issue when it was used five times a days in the oral form. We began recommending that patients use it three times a days and double the dose. In the case of the topical use of the medication, patients need to constantly reapply it. With this type of application, they simply put it in the right place and it stays there.”
In terms of side effect profile, there have been some rare instances, less than 1 percent, of application site irritation. The incidence of headache that has been reported with systemic acyclovir therapy has been 10 percent, and the incidence is much lower with this delivery system.
Disclosures: Dr. Tyring reports that the clinical studies were supported by a grant from Innocutis, the manufacturer of Sitavig. Dr. Attali is an employee of BioAlliance Pharma.