11 December 2017

NRT the lesser of two evils

Addiction Clinical O&G

Prescribing nicotine to a pregnant woman seems counterintuitive; every doctor will remember being taught at medical school that nicotine is toxic to unborn babies.

But compared with the 7,000 chemicals in cigarettes, of which 300 are known to be toxic and 52 carcinogenic, nicotine gum and patches are much safer during pregnancy, an MJA article says.

Conflicting messages from clinical guidelines and uncertainty around safety has meant that around one-quarter of GPs never prescribe nicotine replacement therapy (NRT) for pregnant women.

Greater confidence in prescribing NRT during pregnancy is needed among GPs, the narrative review says.

“Nicotine may not be completely safe for the pregnant mother and fetus, but it is always safer than smoking,” the authors say.

The review provides a step-by-step guide for prescribing NRT to pregnant women.

Start by closely monitoring the woman’s attempt to quit smoking without NRT, the article advises.

If that attempt is unsuccessful, or the woman scores high on the “strength of urges to smoke” and the “frequency of urges” to smoke scales, then oral NRT can be added.

For NRT to be effective, it needs to be taken regularly throughout the day.

For example, a woman smoking 10 cigarettes a day should be instructed to use one piece of gum every 1.5 hours regularly, even if she is not experiencing strong cravings at that time. If a woman knows she is going to be in a situation where the urge to smoke will be strong, such as socialising with friends who smoke, oral NRT can be used 20 minutes beforehand.

Women are started on the lowest dose of NRT that is considered effective, which is using gum containing 4mg of nicotine per piece.

But, given that pregnant women metabolise nicotine at a faster rate than non-pregnant women, higher doses of oral NRT and patches may be necessary, the authors say.

NRT significantly increased smoking cessation rates by around 40% in pregnant women, according to a 2015 Cochrane review of eight studies (including over 2,000 women).

However, when this meta-analysis was restricted to the five placebo-controlled studies, NRT was shown to have a lower, non-significant smoking cessation rate of 28%.

“It is usually under-dosing that is the problem,” said Adjunct Associate Professor Renee Bittoun, a tobacco treatment specialist at the University of Sydney and the president of the Australian Association of Smoking Cessation Professionals.

When combined NRT was prescribed at the correct dose, smoking abstinence rates could be as high as 60% to 70% over 12 months in the general population, she said.

“There are huge jumps when you do combination treatments.”

Combination treatments could include “two patches plus inhalers plus gum … for example,” she said. “There are lots of combinations we do.”

But when only one form of NRT is used in randomised trials, the smoking cessation rate in the general population falls to around 15% to 20%, and just 5% in the placebo group.

“If this were done correctly you would expect to see much better outcomes,” Professor Bittoun said.

While NRT during pregnancy was an area of continuing uncertainty, the RACGP’s smoking cessation guidelines provided practical advice, Professor Nicholas Zwar, a GP and medical dean who chaired the advisory group that produced the guidelines, said.

The guidelines recommend NRT for pregnant women who have made attempts to quit smoking but have been unsuccessful.

Oral NRT is the first-line option, as it has the lowest dose of nicotine, but larger doses or even combination NRT may be needed, the guidelines advise.

Pregnant women had the highest chance of successfully quitting smoking if they were offered medication for nicotine dependence combined with ongoing support from professionals and friends and family, Professor Zwar said.