I’m keen to get to work on this year’s Stocks and Shares ISA FTSE 100 Blue Chip intrigues me. The company is a pharmaceutical giant GSK (LSE: GSK) and it’s been really balmy lately.

I’ve seen this firsthand as I have a petite GSK share in my self-invested personal pension (SIPP). This was a huge disappointment, but I’m tempted to take advantage of the recent problems by lowering the average and buying more.

So what’s wrong with GSK? First, there is the long-term problem that CEO Emma Walmsley has been facing since taking over in 2017. GSK needs to replenish its pipeline of medicines to replace previous blockbusters when patents expire.

Can the GSK share price augment?

This involves putting money into research and development, and Walmsley has raised the funds by freezing a dividend per share of 80p per share for Yonks. This was reduced to 44p in 2022 and to 42p last year. Even though I felt like the “jam tomorrow” approach was the right one, tomorrow never seems to come.

In 2017, the shares of this company, then traded under the name GlaxoSmithKline, were perceived as one of the highest dividend stocks on the stock exchange. FTSE100with a profitability of 6.05%. This is no longer the case. Today’s trailing yield of 4.34% is OK, but has been artificially inflated by recent share price declines.

GSK shares are down 21.43% in the last six months. Although they increased by 7.63% in one year, they decreased by 24.78% in five years.

Looking at the 10-year price chart, I’m not very impressed. GSK’s share price rose several times, only to lose value each time. Overall, it fell from 1,515p to 1,337p over the decade. Not good.

GSK faced two stern problems this year. The first was a class action lawsuit in the US over the claim that a version of his hit heartburn drug had been discontinued Zantac caused cancer. No sooner had this been largely resolved in the form of a $2.2 billion payout on October 9 than Donald Trump won the US presidential election.

Trump is turning against huge pharma

Pharmaceutical stocks fell sharply when, on November 15, Trump nominated Robert F. Kennedy Jr., a vaccine skeptic, as U.S. Secretary of Health. Following this news, GSK’s share price hit its lowest level in two years.

Trump also alarmed the industry with plans to lower drug prices, including making it easier to import drugs into the U.S. from Canada.

This makes investing in GSK risky, although it appears to have priced in the worst-case scenario. The stock appears affordable to trade at just 8.44 times earnings.

16 analysts offering annual GSK share price forecasts set an average target of 1,739p. If this happens, the stock will augment by 30% from then on. However, there is a wide range, from the highest 2160p to the lowest 1350p. However, some of these predictions may precede a landslide victory for Trump.

Of these brokers, seven rate GSK as a “Strong Buy” and only two as a “Strong Sell.” The most popular ruling is “withhold”, adopted by 10 of them. This is also my position. I’ll keep what I have in my SIPP but won’t be buying any more in my Stocks and Shares ISA. GSK has been inflicting pain on investors for too long.