Bupropion is a medication prescribed for major depressive disorder and seasonal affective disorder. It also treats smoking cessation. Many individuals wonder how long it stays in the body. The body’s natural mechanisms break down and remove substances, but this varies based on individual factors.
How Drugs Leave the Body
Pharmacokinetics describes how drugs move through and out of the body. A drug’s half-life (t1/2) is the time it takes for its concentration in the bloodstream to decrease by half. This measurement helps predict how long a substance will exert its effects and remain detectable.
Drugs are eliminated through two main pathways: metabolism and excretion. The liver metabolizes drugs, altering them into forms easier for the body to remove. These altered forms, called metabolites, are then excreted, largely by the kidneys through urine. Most drugs are cleared after about four to five half-lives.
Bupropion’s Journey Out of the System
Bupropion has an elimination half-life of about 21 hours. It is extensively metabolized in the liver into several active compounds that prolong its presence. These include hydroxybupropion (20 hours), erythrohydrobupropion (33 hours), and threohydrobupropion (37 hours), which has the longest half-life.
The parent drug is largely cleared within 4 to 5 days. However, its active metabolites have longer half-lives and can remain in the system longer. Full elimination of these metabolites can take 7 to 10 days, or longer. Therapeutic effects may diminish before complete physical elimination. For drug testing, bupropion and its metabolites are detectable in urine for up to 4 days and in hair follicles for up to 90 days.
Influences on Elimination Time
Several individual factors influence how quickly bupropion and its metabolites are cleared. Genetic makeup affects metabolic enzymes, influencing drug processing efficiency. Liver function is important, as the liver is the primary site for bupropion’s metabolism. Impaired liver function slows drug breakdown, leading to higher concentrations and longer elimination.
Kidney function is also a factor, as kidneys excrete metabolites. Reduced kidney efficiency delays their removal. Age can influence elimination, with older individuals clearing drugs more slowly due to age-related organ changes. Interactions with other medications can also affect elimination. Certain drugs inhibit or induce cytochrome P450 enzymes (CYP2B6 and CYP2D6) involved in bupropion’s metabolism, altering its concentration and clearance.
What to Expect When Stopping Bupropion
Stopping bupropion, especially abruptly, can cause symptoms as the body adjusts to the absence of the medication. These symptoms, known as antidepressant discontinuation syndrome, can include irritability, anxiety, and difficulty sleeping. Other common complaints involve headaches, general body aches or muscle pain, nausea, and dizziness. Some individuals may also report mood swings or unusual sensations described as “brain zaps.”
These symptoms arise as the body adapts to changes in neurotransmitter levels that were influenced by bupropion. To minimize the likelihood and severity of these withdrawal symptoms, it is strongly recommended to avoid suddenly stopping bupropion. Instead, consult a healthcare professional for a gradual tapering plan, slowly reducing the dosage over several weeks. This allows the body more time to adjust, making the discontinuation process smoother and safer.