1                                                                                                                      PRESCRIBING INFORMATION

2           WELLBUTRIN XL^TM

3           (bupropion hydrochloride extended-release tablets)

4            

5           “Patient Information” enclosed.

 

6           DESCRIPTION

7                WELLBUTRIN XL (bupropion hydrochloride), an antidepressant of the aminoketone class,

8           chemically unrelated to tricyclic, tetracyclic, selective serotonin re-uptake inhibitor, or other

9           known antidepressant agents.  Its structure closely resembles that of diethylpropion; it is related

10        to phenylethylamines.  It is designated as (±)-1-(3-chlorphenyl)-2-[1,1-dimethylethyl)amino]-1-

11        propanone hydrochloride.  The molecular weight is 276.2.  The molecular formula is

12        C₁₃H¹⁸ClNO·HCl.  Bupropion hydrochloride powder is white, crystalline, and highly soluble in

13        water.  It has a bitter taste and produces the sensation of local anesthesia on the oral mucosa.  The

14        structural formula is:

15         

                                                                             NHC(CH₃)₃

 

 

  

 

COCHCH₃

 

 

 

 

 

 

 

 

16         

17             WELLBUTRIN XL Tablets are supplied for oral administration as 150-mg and 300-mg,

18        creamy-white to pale yellow extended-release tablets.  Each tablet contains the labeled amount of

19        bupropion hydrochloride and the inactive ingredients: ethylcellulose aqueous dispersion (NF),

20        glyceryl behenate, methacrylic acid copolymer dispersion (NF), polyvinyl alcohol, polyethylene

21        glycol, povidone, silicon dioxide, and triethyl citrate.  The tablets are printed with edible black

22        ink.

23             The insoluble shell of the extended-release tablet may remain intact during gastrointestinal

24        transit and is eliminated in the feces.

 

26        CLINICAL PHARMACOLOGY

27        Pharmacodynamics: Bupropion is a relatively weak inhibitor of the neuronal uptake of

28        norepinephrine, serotonin, and dopamine, and does not inhibit monoamine oxidase.  While the

29        mechanism of action of bupropion, as with other antidepressants, is unknown, it is presumed that

30        this action is mediated by noradrenergic and/or dopaminergic mechanisms.

31        Pharmacokinetics:  Bupropion is a racemic mixture.  The pharmacologic activity and

32        pharmacokinetics of the individual enantiomers have not been studied.  The mean elimination

33        half-life (±SD) of bupropion after chronic dosing is 21 (±9) hours, and steady-state plasma

34        concentrations of bupropion are reached within 8 days.

 

 

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