AstraZeneca has posted a 13% decline in first-quarter revenues to $6.39 billion, due to the loss of exclusivity on key brands, but analysts believe things are starting to improve at the Anglo-Swedish drugmaker.

Core operating profit was down 25% to $2.32 billion, hit by a 60% decline in the antipsychotic Seroquel (quetiapine) franchise to $449 million. Sales of the antihypertensive Atacand (candesartan) sank 49% to $141 million, while in oncology Arimidex (anastrozole) fell 33% to $92 million and Casodex (bicalutamide) decreased 13% to $92 million. Zoladex (goserelin) brought in $240 million (-8%).

However, Iressa (gefitinib) climbed 20% to $168 million and Faslodex (fulvestrant) increased 5% to reach $1571 million. Revenues for the antiulcerant Nexium (esomeprazole) dipped 1% to $940 million.

AstraZeneca's biggest-seller, the cholesterol blockbuster Crestor (rosuvastatin) decreased 11% to $1.32 billion, largely due to loss of exclusivity in Canada where sales sank 90%. The asthma combo Symbicort (budesonide and formoterol) rose 14% to $826 million, while the Onglyza (saxagliptin) diabetes franchise partnered with Bristol-Myers Squibb, brought in $90 million, up 27%.

The recently-launched antiplatelet drug Brilique/Brilinta (ticagrelor), which is seen as crucial to AstraZeneca's future prospects, had sales of $51 million, up from $38 million in the previous quarter.

Pascal Soriot, AstraZeneca's chief executive, said that "we remain focused on our strategic priorities of returning to growth and achieving scientific leadership". He added that "Brilinta, the diabetes franchise, emerging markets, Japan and our respiratory products have all made good progress and we continued to invest in distinctive science that will advance our knowledge of disease physiology and help to identify new drug targets".

AstraZeneca shares were down 2.8% to £32.96 at 9.40am this morning (UK time) but the response from analysts has been pretty positive. Panmure Gordon's Savvas Neophytou noted that gross margin was good in the first quarter and "illustrates the operational cost flexibility chief financial officer Simon Lowth has been instilling for years". He added that there are "no signs, as yet, of the great white hope of accelerating Brilinta sales but it is early days".

Mick Cooper at Edison Investment Research, said the sales decline was expected "and it is still too early to see the real impact of Pascal Soriot". However, he noted that "there has been a flurry of new alliances to enhance its pipeline" and there are signs that Brilinta is starting to improve.