PPAP HCl, ≥98%

Chemical Information:

Technical Information:

Background:

PPAP is a catecholaminergic activity enhancer (CAE) class research compound that selectively increases impulse propagation-mediated dopamine and norepinephrine release in response to action potentials. Unlike stimulant drugs, which release a flood of monoamine neurotransmitters in an uncontrolled manner, PPAP only increases the rate of neurotransmitter amine release that would be released in response to impulse-mediated neuron stimulation.

PPAP can be compared to stimulant drugs like amphetamine in that they both result in a net increase in the rate and magnitude of neurotransmitter release. However, this is where the comparison ends. Amphetamine and amphetamine-like compounds cause a ‘neurotransmitter dump’, in which large stores of neurotransmitter amines are ‘dumped’ into the synapses, regardless of external inputs. PPAP and its sister compounds do not alter the pattern of neurotransmitter release other than to increase the amount of neurotransmitter amines released, and only in response to external impulse mediation. [1]

PPAP was first patented in 1991 by Dr. Jozsef Knoll and his research team as part of a project investigating the catecholamine release-enhancing properties of an earlier invention, deprenyl (selegiline). Selegiline is a potent monoamine oxidase inhibitor (MAOI) but PPAP has no MAOI activity and only exerts a catecholamine activity enhancer (CAE) effect. [2]

The research project was looking further into the indirectly acting sympathomimetic amines, in the phenyl-alkylamine class (similar to endogenous phenylethylamine (PEA) and tyramine). The effect of this group of compounds (including non-endogenous amphetamines) is to release noradrenaline and other transmitter amines to varying degrees. The invention of PPAP proved to be a remarkable discovery. 

The team found that suitable modifications of the chemical structure of phenyl-alkylamines could completely eliminate the dominant characteristic effect of the class of drugs. With appropriate chemical modifications, the primary effect of inducing outflow of transmitter amines was significantly reduced/eliminated and the secondary effect of selective inhibition of the neuronal uptake of sympathomimetic amines was strengthened. The resulting compounds (namely, PPAP and derivatives) exerted a stimulant effect with a novel mechanism of action. [3]

Modes of action:

PPAP is taken up by the catecholamine axon terminal membrane and the vesicular membrane. It does not produce catecholamine-releasing effects but rather acts as a potent inhibitor of the uptake of indirectly-acting sympathomimetic releasers and of catecholamine transmitters. [4]

A 1996 study using rat neuronal cells made some interesting findings relating to PPAP’s mechanisms of action. PPAP’s CAE effect was measured indirectly through quantification of a.) the release of catecholamines from striatum, substantia nigra, tuberculum olfactorium and locus coeruleus; b.) the stimulation-induced release of 3H-noradrenaline from isolated brain stem; and c.) PPAP’s inhibitory effect against tetrabenazine-induced learning deficits in the shuttle box test.

The results showed that PPAP’s CAE effect was unrelated to a.) the inhibition of MAO activity; b.) the inhibition of presynaptic catecholamine receptors; c.) the inhibition of catecholamine uptake; and d.) the release of catecholamines. As a result, the study concluded that PPAP’s primary mechanism of action is through potent stimulation of the action potential-transmitter release coupling in the catecholaminergic neuronal system. [6]

Further Scientific research:

There is still room for further scientific research, especially with regards to PPAP’s mechanisms and effects in healthy humans.

Clinical Reviews:

No clinical reviews or meta-analyses have been published yet, due to a lack of data.

Human studies:

There are no published studies on the effects on PPAP with human participants at this time.

Toxicology:

Dr. Knoll’s patents indicate a low toxicity and a lack of typical stimulant-related side effects. The LD₅₀ of PPAP in rats was as high as 270 mg/kg p.o. and the preferred daily dosage was described as being between 10 mg to 150 mg, with a particular suitability at 30 mg. The patent authors formulated a number of capsules, pills, dragées, etc., containing 30mg PPAP HCl as the active ingredient. [4]

Animal studies:

A 1992 study into the pharmacology of PPAP measured the neuronal uptake of the compound both in vitro and in vivo. Measurements included: a.) the uptake of PPAP into catecholaminergic axon terminals; b.) the inhibition of 3H-noradrenaline and dopamine uptake both in the rat brain and in rabbit pulmonary artery strip, using the rat nictitating membrane as an indicator. Results showed an increase in motility at a PPAP dosage of 2 mg/kg and an inhibitory effect at very doses (50 mg/kg). Drug-drug interactions were noted for PPAP and amphetamine as well as for PPAP and mazindol. Both these interactions reduced the dose-dependent increase in motility.  

Furthermore, the research pointed to PPAP’s ability to facilitate learning and memory retention in vivo. PPAP showed positive results in both reducing tetrabenazine-induced depression and in improving results of the forced swimming test (measuring response to stress/anxiety). The dosage range at which PPAP facilitated positive effects on performance was found to be much broader than that of amphetamine. The authors of the study present PPAP as having potential applications in depression, Alzheimer’s disease, and ADHD. [4]

The early patent by Dr. Knoll et al. described PPAP’s effects as: “stimulating learning ability” and as a “psychostimulant having a new spectrum of effect which can be used in therapy for increasing psyichical activity (learning and retention) and for treating clinical patterns of depression and deficiencies of learning and retention like in Alzheimer’s disease, void of side effects (e.g. due to catecholamine release) of known stimulants”. [7]

References:

• [1] Knoll J, Miklya I, Knoll B, Marko R, Kelemen K. (1996). (-)Deprenyl and (-)1-phenyl-2-propylaminopentane, [(-)PPAP], act primarily as potent stimulants of action potential-transmitter release coupling in the catecholaminergic neurons. Life Sciences, 58(10):817-27.
• [2] Csaba G, Kovacs P, Pallinger E. (2006). Acute and delayed effect of (-) deprenyl and (-) 1-phenyl-2-propylaminopentane (PPAP) on the serotonin content of peritoneal cells (white blood cells and mast cells). Cell Biochemistry and Function, 24(1):49-53.
• [3] Knoll J, et al. (1991). Patent application number 5220068 'A Psychostimulatory Agent’. Available online from https://www.google.com/patents/US5220068
• [4] Knoll J, Knoll B, Török Z, Timár J, Yasar S. (1992). The pharmacology of 1-phenyl-2-propylamino-pentane (PPAP), a deprenyl-derived new spectrum psychostimulant., Arch Int Pharmacodyn Ther, 316:5-29.
• [5] Glennon RA, Battaglia G, Smith JD. (1990). (-)PPAP: a new and selective ligand for sigma binding sites., Pharmacol Biochem Behav, 37(3):557-9.
• [6] Knoll J, Miklya I, Knoll B, Marko R, Kelemen K. (1996). (-)Deprenyl and (-)1-phenyl-2-propylaminopentane, [(-)PPAP], act primarily as potent stimulants of action potential-transmitter release coupling in the catecholaminergic neurons. Life Sciences, 58(10):817-27. 
• [7] Knoll J, et al. (1989). US Patent number US5075338 'A Method of treatment of learning deficiency’. US Patent Office. Available online from https://patents.google.com/patent/US5075338A/en