I’m keen to get to work on this year’s Stocks and Shares ISA allowance and one FTSE 100 blue chip intrigues me. The company is pharmaceutical giant GSK (LSE: GSK) and it’s taken a real beating lately.

I’ve seen that at first hand, because I have a small GSK holding in my self-invested personal pension (SIPP). It’s been a huge disappointment but I’m tempted to take advantage of its recent troubles by averaging down and buying more.

So what’s ailing GSK? First, there’s the long-term problem that CEO Emma Walmsley has faced since taking over in 2017. GSK needs to replenish its drugs pipeline, to replace former blockbusters as they go off patent.

Can the GSK share price recover?

This involves pouring money into research and development, and Walmsley has raised the cash by freezing the dividend per share at 80p per share for yonks. It was cut to 44p in 2022 and 42p last year. While I felt this ‘jam tomorrow’ approach was the right one, tomorrow never seems to arrive.

In 2017, this stock, then trading as GlaxoSmithKline, was viewed as one of the best dividend stocks on the FTSE 100, with a yield of 6.05%. That’s no longer the case. Today’s trailing yield of 4.34% is okay, but it’s been artificially pumped up by recent share price falls.

GSK shares have plunged 21.43% over the last six months. While they’re up 7.63% over one year, they’re down 24.78% over five.

Looking at the 10-year price chart, I’m seriously unimpressed. The GSK share price has spiked on several occasions, only to give up its gains every time. Overall, it’s down over the decade, from 1,515p to 1,337p. Not good.

GSK has faced two big problems this year. The first was a US class action over claims that a discontinued version of its blockbuster heartburn treatment Zantac caused cancer. No sooner was this largely settled in a $2.2bn payout on 9 October, than Donald Trump won the US presidential election.

Trump trades backfires on big pharma

Pharmaceutical stocks plunged across the board when Trump appointed vaccine sceptic Robert F Kennedy, Jr, as US Health Secretary on 15 November. The GSK share price hit a two-year low on the news.

Trump has also worried the industry by plans to lower drug prices, including by making it easier to import medicine to the US from Canada.

This makes it a risky time to invest in GSK although it seems like the worst-case scenario has been priced in. The shares look cheap trading at just 8.44 times earnings.

The 16 analysts offering one-year GSK share price forecasts have set a median target of 1,739p. If that comes to pass, the shares will climb 30% from here. There’s a wide range in there, though, from a high of 2,160p to a low of 1,350p. Some of those forecasts may pre-date Trump’s landslide win, though.

Of these brokers, seven name GSK as a ‘strong buy’, while just two name it a ‘strong sell’. The most popular verdict is ‘hold’, adopted by 10 of them. That’s my position too. I’ll hold what I’ve got in my SIPP, but won’t buy more for my Stocks and Shares ISA. GSK has been on inflicting pain on investors for too long.