Answer

It depends on dose, route of administration, and history of drug misuse.

Both cocaine and the amphetamines developed originally for clinical use (including methamphetamine (or “ice”)) are psychomotor stimulants.¹ They have broadly similar actions at the synaptic level (such as blocking reuptake of dopamine released from the meso-limbo-cortical dopamine terminals), the level of mood and alertness, and the behavioural level. Some other amphetamines (such as phenylamphetamine (mescaline)) have slightly different actions, based, like ecstasy (MDA, MDMA), on a predominantly seratonergic effect.

All can be taken by different routes, including oral, intranasal, intravenous, or smoked (the freebase of cocaine “crack” or methamphetamine “crystal”). In a drug-naive, low dose, intranasal or oral user the stimulant effect would probably be additive at the time of use, with the longer half life of amphetamines giving a much prolonged “high” compared with cocaine by itself. Tolerance in regular users builds up to a great degree, so naive users are at immediate risk of overdose (such as with severe cardiovascular effects) if they take the dose of their more experienced friends, say at a party or club. Fatal overdoses are particularly common if taken in combination with other substances, especially injected heroin (a “snowball” or “speedball”) and abundant alcohol (cocaethylene is produced). A prolonged run of stimulant use, say continuously over a weekend, always produces an unpleasant emotional state very different from the initial euphoria—people who try desperately to prolong the “high” may end up feeling desperate and behave in a pretty wild or frightened way.

In my unpublished work on London stimulant users, dependent drug users significantly preferred cocaine to amphetamine (although it is more expensive)—the first stimulant drug used was predominantly amphetamine in early adolescence. One of the peculiar phenomena of these drugs is priming (early low dose exposure to either one increases the effect of later use of the other), a type of learning. Heavy users of intravenous stimulants show their proconvulsant action—over repeated use, seizures are kindled. This is one (of many) reasons why I would not recommend substitution of prescribed methamphetamine or methylphenidate for former illicit cocaine users.

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