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Methylphenidate: Difference between revisions
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While both [[amphetamine]] and methylphenidate are dopaminergic, it should be noted that their methods of action are somewhat distinct. Specifically, methylphenidate is a dopamine reuptake inhibitor while amphetamine is both a releasing agent and reuptake inhibitor of [[dopamine]] and [[norepinephrine]]. Each of these drugs have a corresponding effect on norepinephrine which are weaker than their effects on dopamine. | While both [[amphetamine]] and methylphenidate are dopaminergic, it should be noted that their methods of action are somewhat distinct. Specifically, methylphenidate is a dopamine reuptake inhibitor while amphetamine is both a releasing agent and reuptake inhibitor of [[dopamine]] and [[norepinephrine]]. Each of these drugs have a corresponding effect on norepinephrine which are weaker than their effects on dopamine. | ||
Methylphenidate's mechanism of action at dopamine-norepinephrine release is still debated, but is fundamentally different from most other phenethylamine derivatives as methylphenidate is thought to increase general firing rate, whereas amphetamine reduces firing rate and reverses the flow of the monoamines via TAAR1 activation.<ref>{{cite journal | vauthors=((Volkow, N. D.)), ((Wang, G. J.)), ((Fowler, J. S.)), ((Gatley, S. J.)), ((Logan, J.)), ((Ding, Y. S.)), ((Hitzemann, R.)), ((Pappas, N.)) | journal=The American Journal of Psychiatry | title=Dopamine transporter occupancies in the human brain induced by therapeutic doses of oral methylphenidate | volume=155 | issue=10 | pages=1325–1331 | date= October 1998 | issn=0002-953X | doi=10.1176/ajp.155.10.1325}}</ref><ref name="Iversen2006"/><ref>Focalin XR review | http://www.pharma.us.novartis.com/product/pi/pdf/focalinXR.pdf</ref><ref>Concerta Xl slow release | http://www.medicines.org.uk/emc/medicine/8382/SPC/Concerta#PHARMACOLOGICAL_PROPSSPC</ref> | Methylphenidate's mechanism of action at dopamine-norepinephrine release is still debated, but is fundamentally different from most other phenethylamine derivatives as methylphenidate is thought to increase general firing rate, whereas amphetamine reduces firing rate and reverses the flow of the monoamines via TAAR1 activation.<ref>{{cite journal | vauthors=((Volkow, N. D.)), ((Wang, G. J.)), ((Fowler, J. S.)), ((Gatley, S. J.)), ((Logan, J.)), ((Ding, Y. S.)), ((Hitzemann, R.)), ((Pappas, N.)) | journal=The American Journal of Psychiatry | title=Dopamine transporter occupancies in the human brain induced by therapeutic doses of oral methylphenidate | volume=155 | issue=10 | pages=1325–1331 | date= October 1998 | issn=0002-953X | doi=10.1176/ajp.155.10.1325}}</ref><ref name="Iversen2006" /><ref>Focalin XR review | http://www.pharma.us.novartis.com/product/pi/pdf/focalinXR.pdf</ref><ref>Concerta Xl slow release | http://www.medicines.org.uk/emc/medicine/8382/SPC/Concerta#PHARMACOLOGICAL_PROPSSPC</ref> | ||
==Subjective effects== | ==Subjective effects== | ||
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}} | }} | ||
|{{effects/cognitive| | |{{effects/cognitive| | ||
*'''[[Effect::Anxiety | |||
*'''[[Effect::Anxiety]]''' - Anxiety is reported with slightly more frequency than other common stimulants like [[amphetamine]] or [[cocaine]]. | |||
*'''[[Effect::Cognitive euphoria]]''' - Compared to other stimulants such as [[amphetamine]], this effect is mild but occasionally occurs at higher or non-orally administered doses . | *'''[[Effect::Cognitive euphoria]]''' - Compared to other stimulants such as [[amphetamine]], this effect is mild but occasionally occurs at higher or non-orally administered doses . | ||
*'''[[Effect::Ego inflation]]''' | *'''[[Effect::Ego inflation]]''' | ||
*'''[[Effect::Emotion suppression]]''' - This is typically most intense at light and common doses, and is more commonly reported from medical usage rather than recreational. | *'''[[Effect::Emotion suppression]]''' - This is typically most intense at light and common doses, and is more commonly reported from medical usage rather than recreational. | ||
*'''[[Effect::Derealisation]]''' - This effect is usually reaported at | *'''[[Effect::Derealisation]]''' - This effect is usually reaported at moderate/high doses. | ||
*'''[[Effect::Focus enhancement]]''' - This component is most effective at low to moderate dosages as anything higher will usually impair concentration. | *'''[[Effect::Focus enhancement]]''' - This component is most effective at low to moderate dosages as anything higher will usually impair concentration. | ||
*'''[[Effect::Wakefulness]]''' | *'''[[Effect::Wakefulness]]''' | ||
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===Dependence and abuse potential=== | ===Dependence and abuse potential=== | ||
In terms of its tolerance, methylphenidate can be used multiple days in a row for extended periods of time and is often prescribed to be used in this way. Tolerance to many of the effects of methyphenidate develops with prolonged and repeated use to the | In terms of its tolerance, methylphenidate can be used multiple days in a row for extended periods of time and is often prescribed to be used in this way. Tolerance to many of the effects of methyphenidate develops with prolonged and repeated use. This results in users having to administer increasingly large doses to achieve the same effects.<ref>{{cite journal | vauthors=((Swanson, J.)), ((Gupta, S.)), ((Guinta, D.)), ((Flynn, D.)), ((Agler, D.)), ((Lerner, M.)), ((Williams, L.)), ((Shoulson, I.)), ((Wigal, S.)) | journal=Clinical Pharmacology and Therapeutics | title=Acute tolerance to methylphenidate in the treatment of attention deficit hyperactivity disorder in children | volume=66 | issue=3 | pages=295–305 | date= September 1999 | issn=0009-9236 | doi=10.1016/S0009-9236(99)70038-X}}</ref> | ||
In the case of acute (i.e. one-off) exposure, it generally takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption).{{citation needed}} Methylphenidate presents cross-tolerance with all dopaminergic stimulants, meaning that after the consumption of methyphenidate all stimulants will have a reduced effect."{{citation needed}} | In the case of acute (i.e. one-off) exposure, it generally takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption).{{citation needed}} Methylphenidate presents cross-tolerance with all dopaminergic stimulants, meaning that after the consumption of methyphenidate all stimulants will have a reduced effect."{{citation needed}} | ||
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Methylphenidate has some potential for abuse due to its action on dopamine transporters. Methylphenidate, like other [[stimulant]]s, increases [[dopamine]] levels in the brain. However, at therapeutic doses this increase is slow and thus euphoria only rarely occurs even when it is administered intravenously.<ref name="Volkow1999">{{cite journal | vauthors=((Volkow, N. D.)), ((Wang, G. J.)), ((Fowler, J. S.)), ((Gatley, S. J.)), ((Logan, J.)), ((Ding, Y. S.)), ((Dewey, S. L.)), ((Hitzemann, R.)), ((Gifford, A. N.)), ((Pappas, N. R.)) | journal=The Journal of Pharmacology and Experimental Therapeutics | title=Blockade of striatal dopamine transporters by intravenous methylphenidate is not sufficient to induce self-reports of “high” | volume=288 | issue=1 | pages=14–20 | date= January 1999 | issn=0022-3565}} | Methylphenidate has some potential for abuse due to its action on dopamine transporters. Methylphenidate, like other [[stimulant]]s, increases [[dopamine]] levels in the brain. However, at therapeutic doses this increase is slow and thus euphoria only rarely occurs even when it is administered intravenously.<ref name="Volkow1999">{{cite journal | vauthors=((Volkow, N. D.)), ((Wang, G. J.)), ((Fowler, J. S.)), ((Gatley, S. J.)), ((Logan, J.)), ((Ding, Y. S.)), ((Dewey, S. L.)), ((Hitzemann, R.)), ((Gifford, A. N.)), ((Pappas, N. R.)) | journal=The Journal of Pharmacology and Experimental Therapeutics | title=Blockade of striatal dopamine transporters by intravenous methylphenidate is not sufficient to induce self-reports of “high” | volume=288 | issue=1 | pages=14–20 | date= January 1999 | issn=0022-3565}} | ||
</ref> The abuse and addiction potential of methylphenidate is therefore significantly lower than other dopaminergic stimulants.<ref name="Volkow1999"/><ref>{{cite journal | vauthors=((Volkow, N. D.)), ((Swanson, J. M.)) | journal=American Journal of Psychiatry | title=Variables That Affect the Clinical Use and Abuse of Methylphenidate in the Treatment of ADHD | volume=160 | issue=11 | pages=1909–1918 | date= November 2003 | url=https://ajp.psychiatryonline.org/doi/abs/10.1176/appi.ajp.160.11.1909 | issn=0002-953X | doi=10.1176/appi.ajp.160.11.1909}}</ref> | </ref> The abuse and addiction potential of methylphenidate is therefore significantly lower than other dopaminergic stimulants.<ref name="Volkow1999" /><ref>{{cite journal | vauthors=((Volkow, N. D.)), ((Swanson, J. M.)) | journal=American Journal of Psychiatry | title=Variables That Affect the Clinical Use and Abuse of Methylphenidate in the Treatment of ADHD | volume=160 | issue=11 | pages=1909–1918 | date= November 2003 | url=https://ajp.psychiatryonline.org/doi/abs/10.1176/appi.ajp.160.11.1909 | issn=0002-953X | doi=10.1176/appi.ajp.160.11.1909}}</ref> | ||
The abuse potential is increased when methylphenidate is crushed and [[Routes_of_administration#Insufflation|insufflated]] (snorted) or [[Routes_of_administration#Intravenous|injected]].<ref name="Morton2000">{{cite journal | vauthors=((Morton, W. A.)), ((Stockton, G. G.)) | journal=Primary Care Companion to The Journal of Clinical Psychiatry | title=Methylphenidate Abuse and Psychiatric Side Effects | volume=2 | issue=5 | pages=159–164 | date= October 2000 | url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC181133/ | issn=1523-5998}}</ref>. It should be noted that due to the fillers in the pill, however, that this can be harmful to the nasal cavities. The primary source of methylphenidate for abuse is the diversion from legitimate prescriptions rather than illicit synthesis. Those who use methylphenidate medicinally generally take it orally as instructed while intranasal and intravenous are the preferred means for recreational use.<ref>{{cite journal | vauthors=((Klein-Schwartz, W.)) | journal=Current Opinion in Pediatrics | title=Abuse and toxicity of methylphenidate: | volume=14 | issue=2 | pages=219–223 | date= April 2002 | url=http://journals.lww.com/00008480-200204000-00013 | issn=1040-8703 | doi=10.1097/00008480-200204000-00013}}</ref> | The abuse potential is increased when methylphenidate is crushed and [[Routes_of_administration#Insufflation|insufflated]] (snorted) or [[Routes_of_administration#Intravenous|injected]].<ref name="Morton2000">{{cite journal | vauthors=((Morton, W. A.)), ((Stockton, G. G.)) | journal=Primary Care Companion to The Journal of Clinical Psychiatry | title=Methylphenidate Abuse and Psychiatric Side Effects | volume=2 | issue=5 | pages=159–164 | date= October 2000 | url=https://www.ncbi.nlm.nih.gov/pmc/articles/PMC181133/ | issn=1523-5998}}</ref>. It should be noted that due to the fillers in the pill, however, that this can be harmful to the nasal cavities. The primary source of methylphenidate for abuse is the diversion from legitimate prescriptions rather than illicit synthesis. Those who use methylphenidate medicinally generally take it orally as instructed while intranasal and intravenous are the preferred means for recreational use.<ref>{{cite journal | vauthors=((Klein-Schwartz, W.)) | journal=Current Opinion in Pediatrics | title=Abuse and toxicity of methylphenidate: | volume=14 | issue=2 | pages=219–223 | date= April 2002 | url=http://journals.lww.com/00008480-200204000-00013 | issn=1040-8703 | doi=10.1097/00008480-200204000-00013}}</ref> | ||
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===Psychosis=== | ===Psychosis=== | ||
{{Main|Stimulant psychosis}} | {{Main|Stimulant psychosis}} | ||
Chronic use (i.e. high dose, repeat dosing) may increase the risk of [[psychosis]].<ref name="Morton2000"/><ref>{{cite journal | vauthors=((Spensley, J.)), ((Rockwell, D. A.)) | journal=New England Journal of Medicine | title=Psychosis during Methylphenidate Abuse | volume=286 | issue=16 | pages=880–881 | date=20 April 1972 | url=https://doi.org/10.1056/NEJM197204202861607 | issn=0028-4793 | doi=10.1056/NEJM197204202861607}}</ref> The safety profile of short-term methylphenidate therapy has been well-established, with short-term clinical trials revealing a very low incidence (0.1%) of methylphenidate-induced psychosis at therapeutic dose levels.<ref>Ritalin & Ritalin-SR Prescribing Information | http://www.pharma.us.novartis.com/product/pi/pdf/ritalin_ritalin-sr.pdf</ref> | Chronic use (i.e. high dose, repeat dosing) may increase the risk of [[psychosis]].<ref name="Morton2000" /><ref>{{cite journal | vauthors=((Spensley, J.)), ((Rockwell, D. A.)) | journal=New England Journal of Medicine | title=Psychosis during Methylphenidate Abuse | volume=286 | issue=16 | pages=880–881 | date=20 April 1972 | url=https://doi.org/10.1056/NEJM197204202861607 | issn=0028-4793 | doi=10.1056/NEJM197204202861607}}</ref> The safety profile of short-term methylphenidate therapy has been well-established, with short-term clinical trials revealing a very low incidence (0.1%) of methylphenidate-induced psychosis at therapeutic dose levels.<ref>Ritalin & Ritalin-SR Prescribing Information | http://www.pharma.us.novartis.com/product/pi/pdf/ritalin_ritalin-sr.pdf</ref> | ||
Psychotic symptoms from methylphenidate can include [[Auditory hallucinations|hearing voices]], [[external hallucinations|visual hallucinations]], urges to harm oneself, severe [[anxiety]], [[mania]], [[disinhibition]], [[delusions|paranoid and grandiose delusions]], [[confusion]], [[emotion suppression|emotional suppression]], increased [[aggression]], and [[irritability]]. | Psychotic symptoms from methylphenidate can include [[Auditory hallucinations|hearing voices]], [[external hallucinations|visual hallucinations]], urges to harm oneself, severe [[anxiety]], [[mania]], [[disinhibition]], [[delusions|paranoid and grandiose delusions]], [[confusion]], [[emotion suppression|emotional suppression]], increased [[aggression]], and [[irritability]]. | ||