Drug giant Pfizer said today that its third-quarter profit fell 14% as sales plunged.

This was mainly due to US generic competition to cholesterol fighter Lipitor, long the world's top-selling drug.

Sales of Lipitor, which is still under patent in some other countries, dropped 71% to $749m.

Sales for more than two-thirds of Pfizer's medicines also declined, most by 10% or more and mainly because of generic competition.

But even Prevnar 13, a shot against ear infections, meningitis and other bacterial diseases that is the top-selling vaccine in history, saw sales fall by 12%, to $868m.

It is still protected by patents, so the drop could indicate that sales have hit a wall as most children in developing countries have already been vaccinated.

The US-based maker of pain reliever Lyrica said net income was $3.21 billion, or 43 cents per share. That was down from $3.74 billion, or 48 cents per share, a year earlier.

Excluding one-time items, earnings were 53 cents per share. Analysts had expected 52 cents. Revenue fell 16% to $13.98 billion, well below expectations for $14.66 billion.

Revenue from prescription drugs dropped 18%, to $12.12 billion, as four of its five segments fared poorly. Sales were down sharply for primary care and specialty care medicines and down by 1-2% for cancer drugs and drugs sold in emerging markets such as China and India.

Only the established products business, which sells popular but off-patent medicines, saw sales rise, by 7% to $2.4 billion.

Lipitor, which once brought in as much as $13 billion a year, got generic competition on November 30, 2011. Pfizer slowed defections while it had limited, slightly cheaper generic competition until May, with big rebates to insurers and offers for most patients staying on Lipitor.

But prices plunged when multiple generics hit the market at the end of May. Pfizer then ended the insurer rebates and most patients switched to generics.

Sales of consumer health products increased 2% to $780m, while veterinary medicine sales fell by 2% to $1.02 billion. Despite the lower sales, Pfizer raised its 2012 profit forecast, to $1.30 to $1.38 per share, from $1.21 to $1.36 per share. But the company reduced the top end of its revenue forecast by $1 billion. The new forecast is for $58 billion to $59 billion.

The company noted its board of directors has authorised a new $10 billion share repurchase programme that will start when Pfizer completes the pending sale of its nutrition business for $11.85 billion to Swiss food and drink giant Nestle. That is expected to happen in the first half of next year.