cAMP: nootropics and compounds | sci-wiki

Drotaverine

Drotaverine (No-Spa) is a benzylisoquinoline antispasmodic, structurally related to papaverine, widely used outside the United States to relax smooth muscle in conditions such as renal and biliary colic, dysmenorrhea and gastrointestinal cramp. Its relaxant action combines PDE4 inhibition (raising cAMP) with L-type calcium-channel blockade. A single 2021 mouse study reported that it reversed streptozotocin-induced Alzheimer-type deficits, but there is no human cognition data.

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Immunomodulator

Apremilast

Apremilast (Otezla) is an orally active PDE4 inhibitor and the first PDE4 drug ever FDA-approved for an immune-dermatologic indication (2014). By raising intracellular cAMP it recalibrates the immune system from the inside out, dialing down TNF-alpha, IL-23 and IL-17 while lifting anti-inflammatory IL-10. That single, elegant switch clears plaque psoriasis, calms psoriatic arthritis, and heals Behcet's oral ulcers, all from a convenient oral tablet that needs no lab monitoring.

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Respiratory

Cilomilast

Cilomilast (Ariflo) is a second-generation oral selective PDE4 inhibitor developed by GlaxoSmithKline for COPD and asthma. It reached FDA review but was rejected in 2003-2004 because the respiratory benefit was small and gastrointestinal side effects were dose-limiting. It is not approved anywhere. There is essentially no human cognition data; a single 2025 mouse study reported that cilomilast reversed scopolamine-induced memory deficits through the cAMP/PKA-CREB-BDNF pathway.

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Dermatological

Crisaborole

Crisaborole (Eucrisa) is a boron-containing, non-steroidal topical PDE4 inhibitor, FDA-approved in December 2016 for mild-to-moderate atopic dermatitis (eczema) in patients aged three months and older. Two pivotal Phase 3 trials showed superior skin clearance and itch relief versus vehicle with a favorable safety profile. Honesty note: this is a skin drug with negligible systemic absorption and no CNS or cognition relevance whatsoever; it is included here only for PDE4-class completeness, not as a nootropic.

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Dermatological

Difamilast

Difamilast (Moizerto) is a selective, PDE4B-preferring topical PDE4 inhibitor and the first PDE4 inhibitor approved in Japan (2021) for atopic dermatitis in patients aged two years and older. Two Phase 3 trials in adults and children showed clear eczema clearance superior to vehicle with a rapid antipruritic effect. Like crisaborole, it is a skin drug with negligible systemic exposure and no CNS or cognition evidence; included here for PDE4-class completeness, not as a nootropic.

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Respiratory

Dyphylline

Dyphylline is a xanthine-derivative bronchodilator that relaxes airway smooth muscle through nonselective phosphodiesterase inhibition and weak adenosine-receptor antagonism. Chemically 7-(2,3-dihydroxypropyl)-1,3-dimethylxanthine, it is a distinct synthetic methylxanthine rather than a theophylline salt, and unlike theophylline it is not metabolized to theophylline in the body but is instead cleared largely unchanged by the kidneys. Marketed for decades under names such as Dilor and Lufyllin (often combined with the expectorant guaifenesin), it is an FDA-approved agent used for the symptomatic relief of bronchospasm in asthma, chronic bronchitis, and chronic obstructive pulmonary disease. Compared with theophylline it is a somewhat weaker bronchodilator on a milligram basis but carries a wider tolerability margin, a shorter half-life, and far fewer drug and smoking interactions because it bypasses hepatic CYP1A2 metabolism. More recent laboratory work has explored repurposing dyphylline as a coronavirus main-protease inhibitor and as a cAMP-raising activator of dormant ovarian follicles.

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Nootropic

Etazolate

Etazolate (EHT-0202) is a fascinating triple-mechanism molecule: a 1970s pyrazolopyridine anxiolytic that ExonHit repurposed for Alzheimer's disease. In one compound it combines PDE4 inhibition, positive allosteric modulation of GABA-A receptors, and stimulation of alpha-secretase, which raises the neurotrophic, neuroprotective fragment sAPPalpha and steers amyloid precursor protein away from toxic amyloid. It is one of the few compounds in this class to have actually completed a placebo-controlled Phase 2 trial in Alzheimer's patients.

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Nootropic

HT-0712

HT-0712 (betamilast) is a PDE4 inhibitor purpose-engineered to be a memory drug. Designed across Inflazyme, Helicon and Dart NeuroScience, it targets the CREB memory pathway with a wider therapeutic window than the notoriously emetic rolipram. In animals it selectively boosts long-term (not short-term) memory in normal and aged mice, and it reached Phase 2 testing in age-associated memory impairment, making it the most deliberately memory-focused candidate in the PDE4 class.

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Stimulant

IBMX

IBMX (3-isobutyl-1-methylxanthine) is a synthetic methylxanthine and nonselective phosphodiesterase inhibitor that also antagonizes adenosine receptors, widely used as a research reagent to raise intracellular cAMP and cGMP. It inhibits most cyclic-nucleotide phosphodiesterase families in the low-micromolar range while comparatively sparing PDE8 and PDE9, and it is a standard component of cell-differentiation cocktails for adipocytes and melanocytes as well as a common positive control in phosphodiesterase and adenosine-receptor pharmacology assays.

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Neuroprotection

Ibudilast

Ibudilast (MN-166, Ketas) is a brain-penetrant, multi-target neuroimmune modulator that stands apart from the pure PDE4 crowd. It inhibits several phosphodiesterases (PDE3/4/10/11) while also blocking macrophage migration inhibitory factor (MIF) and toll-like receptor 4 (TLR4), quieting overactive glia and shifting cytokines toward repair. Marketed for decades in Japan for asthma and post-stroke dizziness, it has advanced internationally as MN-166 through progressive MS, ALS and addiction trials.

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Neuroprotection

Piclamilast

Piclamilast (RP-73401) is a highly potent, subnanomolar pan-PDE4 inhibitor used mainly as a pharmacological reference tool and high-affinity rolipram-binding-site ligand. It was explored for COPD and asthma but never developed. Its most cognition-relevant finding is a 2022 mouse study in which post-ischemia piclamilast was neuroprotective and preserved memory through CREB, an effect abolished by a CREB inhibitor. There is no human data.

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Nootropic

Roflumilast

Roflumilast is a selective PDE4 inhibitor approved as a once-daily oral anti-inflammatory for severe COPD (Daliresp, Daxas) and as a topical treatment for psoriasis and other skin conditions (Zoryve). By blocking PDE4 it raises intracellular cAMP, calming inflammatory cells and, in the brain, boosting the CREB-to-BDNF signaling tied to learning and memory. That neuro angle has turned low, sub-emetic microdoses of roughly 100-250 micrograms into a genuinely intriguing but still preliminary nootropic candidate.

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Nootropic

Rolipram

Rolipram (ZK 62711) is the prototypical PDE4 inhibitor and the reference compound for the entire class. Developed by Schering as an antidepressant in the 1980s, it was abandoned over severe emesis but went on to become the single most-studied molecule in the cAMP/CREB-enhances-memory literature. It reliably converts early- to late-long-term potentiation and rescues memory across Alzheimer, aging and Rubinstein-Taybi models, making it the yardstick every newer PDE4 memory drug is measured against.

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Nootropic

TAK-063

Balipodect (TAK-063) is a selective phosphodiesterase 10A (PDE10A) inhibitor developed by Takeda as a potential antipsychotic for schizophrenia. It has completed phase 2 proof-of-concept testing and, as of 2026, was acquired by Axsome Therapeutics for further development.

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