| DoctorShame 2005-10-27, 6:16 pm |
| Dear Forum,
FYI
Methamphetamine and Sexual Risk Behavior
Treatments for Methamphetamine Use
>From Medscape HIV/AIDS
Expert Columns & Interviews
Methamphetamine: Important Clinical Guidance for Healthcare Providers
Methamphetamine -- The Scope of the Problem
Methamphetamine is a synthetic psychomotor stimulant closely related to
the decongestants ephedrine and phenylpropanolamine.[1] Methamphetamine
can be injected, smoked, snorted, or taken orally or rectally with
effects lasting for up to 12 hours.[2] Administration results in
feelings of euphoria and increased energy.[3]
Amphetamines were first synthesized in 1887, with various amphetamine
compounds being licensed and marketed for medical conditions ranging
from weight loss to asthma.[4] Methamphetamine is synthesized by
converting ephedrine or pseudoephedrine into methamphetamine via a
series of steps usually involving additions of phosphorous and
iodine.[1] This distillation process is commonly employed in large
"meth labs," which have been the focus of most law-enforcement efforts
to control methamphetamine use in the United States. While much
attention has been paid to local, backyard methamphetamine manufacture
in these labs, the US Drug Enforcement Agency (DEA) estimates that 80%
of methamphetamine available in the United States is manufactured in
other countries, primarily Mexico.[5] However, definitive data on
methamphetamine distribution and supply are not available.
Researchers have identified multiple epidemics of amphetamine abuse
dating back to the 1930s.[4,6] The current epidemic originated in
Hawaii and the western United States, but the epidemic is now well
established throughout the country.[7] This spread is paralleled by a
5-fold increase in admissions for stimulant treatment between 1992 and
2002.[8] Methamphetamine now accounts for the majority of amphetamine
used in the United States, with over 12 million adults using
methamphetamine in 2003.[9]
Methamphetamine use is particularly common among men who have sex with
men (MSM), with use as much as 10 times higher than in the general
population.[10] Rates of stimulant use, thought to be mainly
methamphetamine, are high among both HIV-uninfected and HIV-infected
MSM, with 10% to 20% of samples reporting recent methamphetamine
use.[11-13] In a probability-based sample of young MSM in the United
States, 20% reported methamphetamine use in the prior 6 months, with 6%
reporting at least weekly use.[14,15] Studies of targeted populations
of MSM in San Francisco show even higher rates of methamphetamine use.
For example, in a study of circuit parties (weekend-long dance party
events) attended by MSM participants, 43% reported methamphetamine use
in a 72-hour period.[16]
Neurologic Effects of Methamphetamine
The "rush" that follows methamphetamine use is associated with the
release of neurotransmitters, including dopamine, serotonin, and
epinephrine. Most research has focused on the high levels of dopamine
released in the central nervous system (CNS).[17-19] Amphetamines
increase synaptic levels of dopamine by inhibiting the activity of
dopamine reuptake transporters and by increasing release of vesicular
dopamine stores.[6] Brain imaging studies show that amphetamines
increase dopamine levels especially within the nucleus accumbens, the
major reward center in the brain that is thought to be central to
mediating addictive behavior.[20-22] Supporting this hypothesis is that
stimulant-induced euphoria is related to dopamine levels and occupancy
of the dopamine receptor.[19, 23-25]
While acute use of methamphetamine results in increased dopamine
levels, prolonged use results in chronically depressed dopaminergic
activity.[6,26,27] This is thought to be due to the neurotoxic effects
of chronic methamphetamine use, which leads to the reduction of axonal
dopamine transporters, vesicular monoamine transporters, and synthesis
pathways in dopaminergic neurons.[28-30] In animal studies, repeated
exposure to methamphetamines results in degeneration and destruction of
dopamine axon terminals within the CNS.[31-33] Other animal studies
show depleted brain stores of dopamine and long-term decreases in
biochemical markers of dopamine.[34-36]
Health Consequences of Methamphetamine
Methamphetamine use can lead to substantial morbidity and mortality.
While methamphetamine dependence may be characterized by daily use,
many methamphetamine users go on intermittent methamphetamine "binges"
that last 24-72 hours during which they are hypervigilant, do not
sleep, and often engage in high levels of sexual activity. Persons
using methamphetamine can exhibit severe intoxication symptoms that
include agitation, anxiety, and acute paranoia, and these conditions
can progress to mimic acute schizophrenia.[2] Methamphetamine use is
associated with rapid weight loss, likely due to its sympathomimetic
properties.[4] Skin lesions are common among methamphetamine users and
are due to the obsessive, excessive picking and scratching that
accompanies methamphetamine use. These lesions often become infected
and develop into bacterial cellulitis that requires antibiotic
treatment. Methamphetamine use has been associated with
methicillin-resistant Staphylococcus aureus (MRSA) infection.[37]
Many methamphetamine users also experience severe dental decay, which
has been attributed to a number of factors, including: (1) decreased
attention to dental hygiene due to drug use; (2) excessive bruxism
(teeth grinding) and clenching due to the effects of the drug; (3)
increased intake of soft drinks high in sugar that methamphetamine
users often crave; (4) persistent dry mouth due to methamphetamine; and
(5) detrimental effects of residual products used in producing
methamphetamine.[38]
Whatever the underlying causes, the combination of weight loss, skin
lesions, and dental decay can lead to a decline in general appearance
and is likely to account for the rapid aging effect often seen among
heavy methamphetamine users. Additional consequences of acute
methamphetamine use, while rare, can be severe and include convulsions,
stroke, cardiomyopathy, myocardial infarction, and pulmonary
compromise.[39-42]
Methamphetamine withdrawal is well characterized and is associated with
increased anxiety, agitation, and depression.[43,44] Symptoms may
persist, to varying degrees, over several months.[4,45] In animal
studies, depressive behavior following methamphetamine withdrawal has
been linked to decreased dopamine levels in the nucleus accumbens.[46]
It is postulated that methamphetamine relapses are due primarily to the
need to alleviate symptoms by restoring dopamine levels in the CNS to
levels that can be observed in the presence of drug.[47-49]
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