Considering the increasing number of other drugs experiencing extensions of their FDA reviews, it’s no great surprise that Amgen (NASDAQ:AMGN) has announced a delay in the FDA's review of its marketing application for romiplostim, a blood-disorder treatment.

Earlier in the week, Amgen announced that the FDA was pushing back its review of romiplostim by three months -- from an April 23 PDUFA date to July 23. The FDA has been constantly delaying its review of nearly all drugs in the first quarter, so Amgen had probably already guessed that some sort of announcement like this was coming.

Romiplostim is a proposed treatment for immune thrombocytopenic purpura, a disorder caused by low blood-platelet counts. It was subject to an FDA advisory panel hearing less than a month ago, and the panel voted unanimously in favor of its approval. Advisory-panel hearing recommendations are nonbinding, but I'm unaware of any drug that has received a unanimous panel vote of approval and not been approved.

The number of new drug approvals rose at the FDA in the first quarter, but with the current regulatory environment at the agency, it makes no sense for investors to expect that most drugmakers' New Drug Applications or Biologics License Applications will be reviewed in six to nine months, as they were before.

Drugs for nearly every condition being reviewed in the FDA's Center for Drug Evaluation and Research (CDER) -- where most drug-approval decisions are made -- are experiencing delays of one form or another. Cardiome Pharma's (NASDAQ:CRME) heart treatment Kynapid and Adolor's (NASDAQ:ADLR) bowel-disorder drug Entereg are two examples. It appears investors can expect an extra three months, at minimum, for all FDA marketing application reviews and decisions on new drugs, so get used to the extra wait.