Description

Phenidates are a structural subgroup of stimulants. Substances of this effect group produce a stimulatory effect on the central nervous system and modulate the levels and activity of important neurotransmitters such as dopamine, norepinephrine, and serotonin. The action of these neurotransmitters induces a range of excitatory responses in the central nervous system. The differing degrees to which a substance affects these neurotransmitters contribute to the psychostimulant properties of individual substances. Since 2015, one phenidate, namely ethylphenidate, has been placed under international control under Schedule II of the Convention on Psychotropic Substances of 1971.


Chemical structure

Methylphenidate (Ritalin®) is a potent orally active reuptake inhibitor of norepinephrine and dopamine used to treat attention deficit-hyperactivity disorder (ADHD) and narcolepsy. Some analogues of methylphenidate have emerged, with an extension of the carbon side chain (e.g., ethylphenidate, propylphenidate, and isopropylphenidate). Structural modification of the phenidate core provides access to the related pipradrol, desoxypipradrol, and desoxyprolinol psychostimulants (Figure 1). Replacement of the phenyl ring with a 1-naphthyl ring has also been reported. Eleven examples of this class of NPS (specifically seven phenidates, two prolinol, and one pipradrol derivative) have been reported to UNODC.

Figure 1: Chemical structures of methylphenidate derived NPS

Note: The structural differences are highlighted in red.
Source: UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).


Commonly used forms

On the illicit market, central nervous system stimulants are normally encountered in orally active solid-dosage forms (e.g., powder or pills) and can be insufflated or inhaled, swallowed (often wrapped in cigarette papers, colloquially known as “bombing”), smoked, and less commonly injected or used rectally (Figure 2).

Figure 2: Stimulants commonly used forms

Source: UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).


Reported adverse effects

There is limited pharmacological and toxicological data on many phenidate analogues and most pharmacological studies have focused on methylphenidate and, to a lesser degree, ethylphenidate. Self-reported adverse effects of phenidate derivatives include agitation, anxiety, hypertension, tachycardia, and palpitations. Figure 3 shows reported effects of stimulants.

Figure 3: Reported effects of stimulants

Source:UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).

References

UNODC, The challenge of New Psychoactive Substances - A technical update (United Nations publication, 2024).

UNODC, Early Warning Advisory on New Psychoactive Substances Dashboard, accessed 27 September 2024.

Last update: 30/09/2024