What is the Amphetamine Half Life?

While amphetamines offer a range a treatment benefits, amphetamines exist as one of the most addictive drug classes on the market. Part of the reason has to do with how these drugs interact with the brain and body’s systems.

These effects all play into amphetamine half life in terms of how the body metabolizes the drug. Other factors affecting amphetamine half life include:

  • A person’s overall body chemistry
  • Health status
  • Drug usage patterns
  • The body’s metabolism rate

Ultimately, amphetamine half life affects how long the drug stays in the system, which can have grave implications for chronic drug users.

Amphetamine Effects

Amphetamine half life indicates how long it takes for half of any given dosage amount to leave the body’s system. The effects of these drugs on the body as a whole have a lot to do with amphetamine half life durations.

According to the National Center for Biotechnology Information, amphetamines work as central nervous system stimulants, speeding up chemical activities throughout the body. When ingested, amphetamines stimulate the production of dopamine and norepinephrine neurotransmitter chemicals from individual brain cell sites.

The “high” brought on by amphetamines stays in effect for as long as the drug remains in the system, though intensity levels tend to dwindle once amphetamine half life is reached. Depending on the drug and the amount taken, these effects can last anywhere from eight to 24 hours.

Amphetamine Effects vs. Cocaine Effects

As stimulant-type drugs, amphetamines and cocaine produce near identical effects in the brain. The two drug types do however differ in terms of duration of effects. Classification-wise, amphetamines belong to the Schedule II class of narcotic substances, while cocaine falls under the Schedule I class, the most addictive drugs in existence.

While a cocaine “high” only lasts for one to two hours, amphetamine effects can last much longer. Not surprisingly, amphetamine half life runs considerably longer than cocaine’s, with copious amounts of neurotransmitter chemicals flooding the brain and central nervous system for the duration of an amphetamine “high.”

Usage Methods

Amphetamine Half Life

Amphetamine half life is closely related to its effects.

When used for treatment purposes, amphetamines typically come in pill form. For recreational use, amphetamines can be snorted, smoked or injected. The type of method used can shorten or lengthen the amphetamine half life period.

According to the National Highway Traffic Safety Administration, oral administration of amphetamines carries a half life of 10.1 hours on average. When taken in injection form, the average amphetamine half life is 12.2 hours. Part of the reason for these differences has to do with the types of metabolites that form during metabolism, as some metabolites take longer to break down than others.

pH Levels

Metabolism processes rely on a series of chemical interactions to break down, use and eliminate materials from the body. Any one chemical interaction requires certain conditions be present in order for the process to take place. With amphetamine metabolism processes, the body’s pH levels affect amphetamine half life times.

A pH level measures acidity versus alkalinity. In terms of amphetamine half life, someone with an acidic-prone body chemistry metabolizes amphetamines at a faster rate than someone with a pH that leans towards the alkaline side. These differences in turn affect amphetamine half life, with half life times running shorter for acidic pH levels.

Average Amphetamine Half Life

According to the American College of Neuropsychopharmacology, the average half life for amphetamine falls within the 12 to 14 hour range for people with a pH level of six. The pH scale runs from 0.0 to 14.0 with 0.0 designated as highly acidic and 14.0 high alkaline. A level of six, though slightly acidic, falls towards the middle of the pH scale.

Tolerance Effects on Amphetamine Half Life in Chronic Drug Users

In the case of chronic amphetamine use, half life durations run longer due to the increased tolerance levels chronic users develop over time. Tolerance levels have to do with the brain’s ability to “tolerate” larger doses of amphetamine with ongoing drug use.

With chronic amphetamine use, high tolerance levels not only alter the brain’s chemistry, but also the chemical make-up of the body’s cells and tissues. Part of the reason for this has to do with amphetamine being a fat-soluble material, which enables the drug to move through the membrane materials that encase the body’s cells.

Over time, body cells and tissues develop an affinity for amphetamine allowing the substance to store up inside these areas in residue form. These conditions inevitably extend the drug’s half life duration.

Amphetamine Half Life Cycles

Half life cycles provide a means for determining how long it takes the body to eliminate amphetamine from the system. A half life cycle equals a half-life period, so a half life of six hours would represent one half life cycle.

On average, it takes four half life cycles for the body to eliminate 90 to 95 percent of any one dose of amphetamine. For someone with a pH of six, one half life cycle equals 12 to 14 hours. This means it would take anywhere from 48 to 56 hours for the body to eliminate 90 to 95 percent of the drug from the system.

Drug Testing Considerations

The number of factors affecting amphetamine half life periods make it difficult to specify an exact time interval across the board. For people required to undergo drug testing, it helps to know the drug detection time windows for any one type of drug testing tool.

Drug tests use different types of samples to detect the presence of drugs, with blood, urine, saliva and hair being the most commonly used sample types. Time windows for each sample type go as follows:

  • Blood – can detect the presence of amphetamines for up to 12 hours after the last drug dose
  • Urine – two to five days
  • Saliva – one to five days
  • Hair follicles – up to 90 days after the last drug dose

Bingeing & Health Risks

Amphetamine tolerance levels rise quickly, placing users at increasing risk for serious health complications. As amphetamine half life durations run longer, the drug’s stimulant effects intensify, especially when users engage in bingeing practices.

With bingeing, users ingest multiple doses of the drug to produce the desired “high” effects. In the process, the rise in blood pressure and heart rates places an incredible strain on the body’s cardiovascular system, according to the Institute for Substance Abuse Treatment Evaluation. Under these conditions, the risk of stroke and heart attack run incredibly high.