TRENTON, N.J. — Drugmaker Pfizer is continuing its shopping spree with its fourth acquisition since the April collapse of its planned $160 billion deal to buy rival Allergan and move its headquarters, on paper, to Allergan's base in lower-tax Ireland.

In its second deal this week, New York-based Pfizer said it's buying rights to AstraZeneca's portfolio of approved and experimental antibiotic and antifungal pills, a move to boost Pfizer's business in one of its priority areas. The deal is valued in excess of $1.5 billion, including rights to sell the medicines in most countries outside the U.S., royalties and other payments.

The acquisition indicates a thawing of relations between the two companies barely two years after U.K.-based AstraZeneca fought off Pfizer's hostile takeover attempt.

Pfizer had planned that $119 billion acquisition as a so-called “tax inversion” enabling Pfizer to slash its U.S. tax bill by moving its nominal headquarters — but not its corporate offices or executives — to England.

The tax inversion strategy had been hot in corporate America for a few years, but it's cooled down since the U.S. Treasury Department in early April issued new tax rules to block the biggest U.S. drugmaker from becoming a corporate citizen of Ireland as part of the Allergan deal.

Allergan is technically based in Dublin, but it's the result of a tax inversion merger and operates from Parsippany, N.J.

Under the deal announced Wednesday, AstraZeneca will receive an upfront payment of $550 million.

Pfizer will get rights to some medicines in development and approved ones including Merrem, for treating bacterial meningitis and serious infections of the skin and stomach; Zinforo, for pneumonia and complex skin and soft tissue infections; and Zavicefta, a combination antibiotic the European Union just approved for treating serious bacterial infections.

Luke Miels, the head of the antibiotics business unit at AstraZeneca, said in a statement the company is “pleased that our strong science in antibiotics will continue to serve a critical public health need through Pfizer's dedicated focus on infectious diseases.”

Pfizer's other recent deals include:

?On Monday, it announced a $14 billion deal to buy San Francisco-based Medivation, which develops pills for treating various cancers. That's a priority area, but Pfizer is playing catch-up with rivals dominating the new generation of targeted cancer medicines.

?On Aug. 1, Pfizer announced a deal worth $150 million upfront and potentially another $495 million to acquire what Pfizer didn't already own of Bamboo Therapeutics of Chapel Hill, N.C. It is developing potentially lucrative gene therapies for rare diseases. Pfizer aims to become a leader in gene therapy.

?In June, Pfizer completed a $5.2 billion acquisition of Palo Alto, Calif.-based Anacor Pharmaceuticals, which could get a new eczema drug, crisaborole, approved by January. Pfizer also got topical toenail fungus treatment Kerydin and some other drugs in early testing.

Pfizer shares ended down about 1 percent to $34.82 on Wednesday.