Roflumilast

Absorption

After a 500mcg dose, the bioavailability of roflumilast is about 80%. In the fasted state, maximum plasma concentrations are reached in 0.5 to 2 hours, while in the fed state, Cmax is reduced by 40%, Tmax is increased by one hour, and total absorption is unchanged.
Applied topically, the mean systemic exposure for roflumilast and its N-oxide metabolite in adults was 72.7 ± 53.1 and 628 ± 648 h?ng/mL, respectively. The mean systemic exposure for roflumilast and its N-oxide metabolite in adolescents was 25.1 ± 24.0 and 140 ± 179 h?ng/mL, respectively.

Toxicity

There are no data regarding overdosage with orally administered roflumilast. Phase I studies in which roflumilast was administered at single doses up to 5000 mcg showed an increase in the incidence of headache, gastrointestinal disorders, dizziness, palpitations, lightheadedness, clamminess, and arterial hypotension. In the event of an overdose, administer support medical care as soon as possible. Hemodialysis is unlikely to be of benefit given the extensive protein binding of roflumilast.

Description

Roflumilast is a selective, orally active PDE4 inhibitor thatwas approved in Germany in July 2010 as an add-on to bronchodilator treatment for maintenance therapy of severe chronic obstructive pulmonary disorder (COPD) associated with chronic bronchitis in adult patients with a history of frequent exacerbations .
Roflumilast and its primary metabolite roflumilast N-oxide are potent and competitive inhibitors of PDE4 and are equipotent against PDE4A, B, andD but inactive against PDE4C and the other ten members of the PDE family (PDEs 1–3, 5–11). Despite its inhibition of PDE4D (IC₅₀=0.80 nM, N-oxide IC₅₀=2.0 nM), roflumilast shows the lowest incidence of nausea (3–5%) among the PDE4 inhibitors investigated in clinical trials.Anti-inflammatory effects of roflumilast have been demonstrated in preclinical cellular and animal models. Roflumilast is synthesized in four steps from 3-(cyclopropylmethoxy)-4-hydroxybenzaldehyde. The difluoromethyl ether is introduced by alkylation of the free phenolic group with chlorodifluoromethane and base. The aldehyde moiety is oxidized to the benzoic acid, which is then converted to an acid chloride and coupled with 3,5-dichloro-4-aminopyridine. Roflumilast is rapidly absorbed and metabolized to its active metabolite, roflumilast N-oxide. Metabolism is mediated by CYP3A4 and CYP1A2.

The Uses of Roflumilast

Roflumilast (Daxas) is a selective inhibitor of PDE4 with IC50 of 0.2-4.3 nM.

Indications

Oral roflumilast is indicated to reduce the risk of COPD exacerbations in patients with severe COPD associated with chronic bronchitis and a history of exacerbations.
Topical roflumilast is indicated to treat plaque psoriasis, including intertriginous areas, in patients 12 years of age and older.

Background

Roflumilast is a highly selective phosphodiesterase-4 (PDE4) inhibitor. PDE4 is a major cyclic-3',5′-adenosinemonophosphate (cyclic AMP, cAMP)-metabolizing enzyme expressed on nearly all immune and pro-inflammatory cells, in addition to structural cells like those of the smooth muscle or epithelium. The resultant increase in intracellular cAMP induced by roflumilast's inhibition of PDE4 is thought to mediate its disease-modifying effects, although its precise mechanism of action has yet to be elucidated.
The oral formulation of roflumilast is indicated to manage the chronic obstructive pulmonary disease. It was first approved by the EMA in July 2010, and by the FDA in January 2018. Roflumilast topical cream is indicated to treat plaque psoriasis. It was first approved by FDA in July 2022 and by Health Canada in April 2023.

What are the applications of Application

Roflumilast is a selective inhibitor of PDE4 (phosphodiesterase 4)

Pharmacokinetics

Roflumilast and its active metabolite, roflumilast N-oxide, increase cyclic adenosine-3′, 5′-monophosphate (cAMP) in affected cells by inhibiting PDE4. They are highly selective for PDE4 and are effectively inactive against PDEs 1, 2, 3, 5, and 7.

Metabolism

Roflumilast is metabolized to roflumilast N-oxide, the active metabolite of roflumilast in humans, by CYP3A4 and CYP1A2. The N-oxide metabolite is less potent than its parent drug in regards to PDE4 inhibition, but its plasma AUC is approximately 10-fold greater.