A phosphodiesterase inhibitor is a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE), thereby preventing the inactivation of the intracellular second messengers, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) by the respective PDE subtype(s). The ubiquitous presence of this enzyme means that non-specific inhibitors have a wide range of actions, the actions in the heart, and lungs being some of the first to find a therapeutic use.
Tadalafil, sold under the brand name Cialis among others, is a medication used to treat erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension. It is taken by mouth. Onset is typically within half an hour and the duration is up to 36 hours.
Fluticasone/salmeterol, sold under the brand name Advair among others, is a fixed-dose combination medication containing fluticasone propionate and salmeterol. It is used in the management of asthma and chronic obstructive pulmonary disease (COPD). It is used by inhaling the medication into the lungs.
Salmeterol is a long-acting β2 adrenergic receptor agonist (LABA) used in the maintenance and prevention of asthma symptoms and maintenance of chronic obstructive pulmonary disease (COPD) symptoms. Symptoms of bronchospasm include shortness of breath, wheezing, coughing and chest tightness. It is also used to prevent breathing difficulties during exercise.
A phosphodiesterase type 5 inhibitor is a vasodilating drug that works by blocking the degradative action of cGMP-specific phosphodiesterase type 5 (PDE5) on cyclic GMP in the smooth muscle cells lining the blood vessels supplying various tissues. These drugs dilate the corpora cavernosa of the penis, facilitating erection with sexual stimulation, and are used in the treatment of erectile dysfunction (ED). Sildenafil was the first effective oral treatment available for ED. Because PDE5 is also present in the smooth muscle of the walls of the arterioles within the lungs, two PDE5 inhibitors, sildenafil and tadalafil, are FDA-approved for the treatment of pulmonary hypertension. As of 2019, the wider cardiovascular benefits of PDE5 inhibitors are being appreciated.
Cyclic guanosine monophosphate-specific phosphodiesterase type 5 is an enzyme from the phosphodiesterase class. It is found in various tissues, most prominently the corpus cavernosum and the retina. It has also been recently discovered to play a vital role in the cardiovascular system.
Long-acting β adrenoceptor agonists are usually prescribed for moderate-to-severe persistent asthma patients or patients with chronic obstructive pulmonary disease (COPD). They are designed to reduce the need for shorter-acting β2 agonists such as salbutamol (albuterol), as they have a duration of action of approximately 12 hours in comparison with the 4-to-6-hour duration of salbutamol, making them candidates for sparing high doses of corticosteroids or treating nocturnal asthma and providing symptomatic improvement in patients with COPD. With the exception of formoterol, long-acting β2 agonists are not recommended for the treatment of acute asthma exacerbations because of their slower onset of action compared to salbutamol. Their long duration of action is due to the addition of a long, lipophilic side-chain that binds to an exosite on adrenergic receptors. This allows the active portion of the molecule to continuously bind and unbind at β2 receptors in the smooth muscle in the lungs.
Levosalbutamol, also known as levalbuterol, is a short-acting β2 adrenergic receptor agonist used in the treatment of asthma and chronic obstructive pulmonary disease (COPD). Evidence is inconclusive regarding the efficacy of levosalbutamol versus salbutamol or salbutamol-levosalbutamol combinations, though levosalbutamol is believed to have a better safety profile due to its more selective binding to β2 receptors versus β1.
Rolipram is a selective phosphodiesterase-4 inhibitor discovered and developed by Schering AG as a potential antidepressant drug in the early 1990s. It served as a prototype molecule for several companies' drug discovery and development efforts. Rolipram was discontinued after clinical trials showed that its therapeutic window was too narrow; it could not be dosed at high enough levels to be effective without causing significant gastrointestinal side effects.
A PDE3 inhibitor is a drug which inhibits the action of the phosphodiesterase enzyme PDE3. They are used for the therapy of acute heart failure and cardiogenic shock.
Doxofylline is a phosphodiesterase inhibiting bronchodilator used in the treatment of chronic respiratory diseases such as asthma and COPD. Like theophylline, it is a xanthine derivative.
Roflumilast, sold under the trade name Daxas among others, is a drug that acts as a selective, long-acting inhibitor of the enzyme phosphodiesterase-4 (PDE-4). It has anti-inflammatory effects and is used as an orally administered drug for the treatment of inflammatory conditions of the lungs such as chronic obstructive pulmonary disease (COPD).
Mardepodect is a drug which was developed by Pfizer for the treatment of schizophrenia. It acts as a phosphodiesterase inhibitor selective for the PDE10A subtype. The PDE10A enzyme is expressed primarily in the brain, mostly in the striatum, nucleus accumbens and olfactory tubercle, and is thought to be particularly important in regulating the activity of dopamine-sensitive medium spiny neurons in the striatum which are known to be targets of conventional antipsychotic drugs. Older PDE10A inhibitors such as papaverine have been shown to produce antipsychotic effects in animal models, and more potent and selective PDE10A inhibitors are a current area of research for novel antipsychotic drugs which act through a different pathway to conventional dopamine or 5-HT2A antagonist drugs and may have a more favourable side effects profile. Mardepodect is currently one of the furthest advanced PDE10A inhibitors in development and has progressed through to Phase II clinical trials in humans. In 2017, development of mardepodect for the treatment of schizophrenia and Huntington's disease was discontinued.
Losmapimod (GW856553X) is an investigational drug being developed by Fulcrum Therapeutics for the treatment of facioscapulohumeral muscular dystrophy (FSHD); a phase III clinical trial is pending approval. Losmapimod selectively inhibits enzymes p38α/β mitogen-activated protein kinases (MAPKs), which are modulators of DUX4 expression and mediators of inflammation.
A phosphodiesterase-4 inhibitor, commonly referred to as a PDE4 inhibitor, is a drug used to block the degradative action of phosphodiesterase 4 (PDE4) on cyclic adenosine monophosphate (cAMP). It is a member of the larger family of PDE inhibitors. The PDE4 family of enzymes are the most prevalent PDE in immune cells. They are predominantly responsible for hydrolyzing cAMP within both immune cells and cells in the central nervous system.
Piclamilast, is a selective PDE4 inhibitor. It is comparable to other PDE4 inhibitors for its anti-inflammatory effects. It has been investigated for its applications to the treatment of conditions such as chronic obstructive pulmonary disease, bronchopulmonary dysplasia and asthma. It is a second generation compound that exhibits structural functionalities of the PDE4 inhibitors cilomilast and roflumilast. The structure for piclamilast was first elucidated in a 1995 European patent application. The earliest mention of the name "piclamilast" was used in a 1997 publication.
Filaminast was a drug candidate developed by Wyeth-Ayerst. It is a phosphodiesterase 4 inhibitor and an analog of rolipram, which served as a prototype molecule for several development efforts. It was discontinued after a Phase II trial showed that its therapeutic window was too narrow; it could not be dosed high enough without causing significant side effects, which was a problem with the rolipram class of molecules.
Olodaterol is an ultra-long-acting β adrenoreceptor agonist (ultra-LABA) used as an inhalation for treating people with chronic obstructive pulmonary disease (COPD). It is manufactured by Boehringer Ingelheim.
Dupilumab, sold under the brand name Dupixent, is a monoclonal antibody blocking interleukin 4 and interleukin 13, used for allergic diseases such as eczema, asthma and nasal polyps which result in chronic sinusitis. It is also used for the treatment of eosinophilic esophagitis and prurigo nodularis.
Phosphodiesterases (PDEs) are a superfamily of enzymes. This superfamily is further classified into 11 families, PDE1 - PDE11, on the basis of regulatory properties, amino acid sequences, substrate specificities, pharmacological properties and tissue distribution. Their function is to degrade intracellular second messengers such as cyclic adenine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) which leads to several biological processes like effect on intracellular calcium level by the Ca2+ pathway.
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