Wellbutrin SR

Wellbutrin SR is a sustained-release tablet whose active ingredient is bupropion hydrochloride. Bupropion is unusual among medicines affecting mood and behaviour: it works by reducing the re-uptake of noradrenaline and dopamine, and does not act mainly on serotonin. The SR indicates a release that is spread across the day. In Britain, the closest licensed product is the 150 mg prolonged-release bupropion tablet whose SmPC covers smoking cessation, and the information below follows that document.

The 150 mg tablet is the only one listed, available in 30, 60, 90, 120, 180 or 360. Wellbutrin SR 150 mg is the same strength as the UK tablet called Zyban, though a British prescriber would choose among UK-licensed products, not an imported brand. The name Wellbutrin does not appear on the electronic medicines compendium. A product made for another market can carry different excipients and different leaflet wording, so the strip and carton need reading on arrival.

For smoking cessation, the schedule is 150 mg once a day on days one to six, then 150 mg twice a day, with the two doses at least eight hours apart. A single dose is capped at 150 mg, and 300 mg is the limit for a whole day. Treatment lasts seven to nine weeks, and it is stopped if there has been no benefit by the seventh week. People who are elderly, or who have impaired liver function, keep to 150 mg once a day, and so does anyone with kidney impairment of any degree. The SmPC does not cover those under 18. Tablets are swallowed whole.

Bupropion lowers the seizure threshold, so the SmPC rules it out for anyone with a current seizure disorder or any history of seizures, a central nervous system tumour, or abrupt withdrawal from alcohol or medicines associated with withdrawal seizures, particularly benzodiazepines. It is also contraindicated in severe hepatic cirrhosis, in anyone with a history of bipolar disorder or a current or previous diagnosis of bulimia or anorexia nervosa, and with any other bupropion-containing medicine. A monoamine oxidase inhibitor must be stopped before bupropion starts: a gap of 14 days for irreversible types and at least 24 hours for reversible ones.

Wellbutrin SR strongly inhibits CYP2D6, so levels can rise for medicines handled by that enzyme, and tamoxifen may become less effective because less of its active form is made. Drugs that also lower the seizure threshold, such as certain antipsychotics, antidepressants, theophylline and steroids, add to the risk, while enzyme inducers and inhibitors change bupropion levels themselves. When it is combined with nicotine replacement, blood pressure should be checked, as the pair can push it higher. Tell the prescriber about everything you use, including herbal products and recreational drugs. The dose in the SmPC is the one for smoking cessation, so any other reason for taking bupropion falls outside that document and has to be discussed with a prescriber before the first tablet.

Trouble sleeping, headache, a dry mouth, nausea, dizziness, tremor and anxiety are the commoner reactions. Taking the second daily dose well before bedtime, as the dosing gap allows, may ease sleep problems. Rash, swelling of the face, chest pain or a seizure needs urgent medical attention. The decision to use Wellbutrin SR belongs to your doctor or prescriber, who will also decide for how long it should be taken and how it is stopped.