Bupropion chemical structure
Find information on thousands of medical conditions and prescription drugs.

Wellbutrin

Bupropion (amfebutamone) is an antidepressant of the amino ketone class, chemically unrelated to tricyclics or selective serotonin reuptake inhibitors (SSRIs). It is similar in structure to the stimulant cathinone, and to phenethylamines in general. It is a chemical derivative of diethylpropion, an amphetamine-like substance used as an anorectic. Bupropion is both a dopamine reuptake inhibitor and a norepinephrine reuptake inhibitor. more...

Home
Diseases
Medicines
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
Warfarin
Wellbutrin
Westadone
Winstrol
Wydase
Wymox
X
Y
Z

History

Bupropion was first synthesized by Burroughs Research in 1966, and patented by Burroughs-Wellcome (later Glaxo-Wellcome, and, as of 2000, GlaxoSmithKline) in 1974. It was approved by the FDA in 1985 and marketed under the name Wellbutrin as an antidepressant, but clinical trials indicated that incidence of seizure was two to four times greater than other antidepressants and the drug was quickly pulled from the market. It was subsequently discovered that reducing the dose by about half greatly reduced the risk of seizures. Glaxo then developed a sustained-release (SR) version of Wellbutrin which releases bupropion hydrochloride at a slower rate. The SR formulation is taken twice a day, in order to further decrease the possibility of adverse side effects and seizures. It is also available in generic form (Bupropion SR). Extended Release bupropion, Wellbutrin XL, is the most recent formulation of bupropion and is taken orally once a day. Because of this altered mechanism of delivery and reduced dosing, incidence of seizures with bupropion is comparable to, and in some cases, lower than that of other antidepressants.

In 1997, bupropion HCl was approved by the FDA for use as a smoking cessation aid. Glaxo subsequently marketed the drug under the name Zyban to help people stop smoking tobacco by reducing the severity of craving and addiction/withdrawal symptoms. It can be used in combination with nicotine replacement therapies. Bupropion treatment course lasts for seven to twelve weeks, with the patient halting the use of tobacco around ten days into the course.

Bupropion is also being investigated as a weight loss drug.

Mode of action

Bupropion is a selective catecholamine (norepinephrine and dopamine) reuptake inhibitor. It has only a small effect on serotonin reuptake. It does not inhibit MAO. The actual mechanism behind bupropion's action is not known, but it is thought to be due to the effects on dopaminergic and noradrenergic mechanisms.

Pharmacokinetics

Bupropion is metabolised in the liver. It has at least three active metabolites: hydroxybupropion, threohydrobupropion and erythrohydrobupropion. These active metabolites are further metabolised to inactive metabolites and eliminated through excretion into the urine. The half-life of bupropion is 20 hours as is hydroxybupropion's. Threohydrobupropion's half-life is 37 hours and erythrohydrobupropion's 33 hours.

Chronic hepatotoxicity in animals

In rats receiving large doses of bupropion chronically, there was an increase in incidence of hepatic hyperplastic nodules and hepatocellular hypertrophy. In dogs receiving large doses of bupropion chronically, various histologic changes were seen in the liver, and laboratory tests suggesting mild hepatocellular injury were noted.

Read more at Wikipedia.org


[List your site here Free!]


Fat pharms: weight gain is the dreaded side effect of some psychotropics
From Psychology Today, 5/1/05 by Brenda Goodman

THE STRESS OF working at a turbulent office finally dragged 37-year-old Maggie Little * under. For the second time in her life, she recognized the smothering symptoms of depression--slowness, a bleak outlook and lack of interest in fun. Her doctor prescribed Lexapro, a selective serotonin reuptake inhibitor, or SSRI.

The pill quickly kicked in. It was "a miracle," she says. Six months later, Little still loves Lexapro, but she's desperate to switch to another drug. Like many people using SSRIs, she gained a significant amount of weight--40 pounds.

Weight gain has long been a bane of psychotropic drug treatment. Mood stabilizers such as lithium and clozapine are among the worst offenders, causing up to 50 percent of all long-term users to become obese. Patients on older tricyclic antidepressants can expect a steady gain of one to three pounds per month. But the medical community was caught off guard when patients on newer antidepressants complained the pounds were piling on.

If anything, says Charles Raison, a psychiatrist with Emory University in Atlanta, drugs such as Prozac and Zoloft were believed to cause weight loss. indeed, many antidepressants seem to be associated with an initial small loss, but new studies show that over months, patients not only regain what they lose, but add to it--sometimes dramatically. "It's not always the fault of the drug," says Raison. "Depression can be, all by itself, an incredible diet. When [patients] start to feel better again, their appetite increases."

The metabolic pathway at work is a mystery, although current theories include resistance to the hormones insulin and leptin. One study found that those most vulnerable to antidepressant-induced weight gain are women and patients who were already overweight. On the bright side, gaining some extra padding is usually linked to the drug's efficacy. "A few extra pounds usually means the drug is doing something," says Raison. But he says many of his patients would rather be sad than fat.

Exercise and diet can help, of course. The drug orlistat, or Xenical, which blocks the body's ability to absorb dietary fat, also shows promise. Switching drugs may also provide some relief.

* name has been changed

HEAVY HITTERS

COPYRIGHT 2005 Sussex Publishers, Inc.
COPYRIGHT 2005 Gale Group

Return to Wellbutrin
Home Contact Resources Exchange Links ebay