The gutter oil drug scandal may affect the whole pharmaceutical sector to some extent, analysts said Monday, after media reports claimed several more companies including Qilu Pharmaceutical Co and Charoen Pokphand Group (CP Group) are involved in the scandal.

Earlier, Henan Huikang, a distributor of Shandong underground oil network, was exposed to having supplied gutter oil, which is used in the making of a special product called 7-ACA, an intermediate needed in producing antibiotics.

"If more producers are exposed to be involved in the scandal, the sales and image of the pharma sector will suffer," Wei Guangju, a senior consultant at Adfaith Management Consulting, told the Global Times Monday.

"The capital market will also respond negatively to the news," Wei said, noting that the shares of Shenzhen-based Joincare Pharmaceutical Group dropped 10 percent Friday on the news that its subsidiary in Jiaozuo, Henan Province has purchased 145 million yuan worth of gutter oil from Huikang for antibiotics production.

The Jiaozuo subsidiary of Joincare was the biggest client of Huikang and purchased half of the total volume of gutter oil produced by Huikang since early 2010 to July 2011.

Qilu, the latest suspect in the scandal, said Friday in a statement on its website that it is not aware if its suppliers, all of which are license holders, mix gutter oil in the soybean oil it procures from them.

The company, however, "is willing to take responsibility for any resulting flaws in products made from such oil," it said.

The group could not be reached for comment Monday. Another company, CP Group, whose six subsidiaries have reportedly bought oil from Huikang, said it has stopped cooperation with Huikang, Oriental Morning Post reported.

The State Food and Drug Administration announced Saturday it is investigating into Joincare production.

Some experts told media that there is no final judgment on the impact and it is barely possible to detect any gutter oil in the final medicine. Others, however, insisted that the public has a right to know the facts.

A wide price gap exists between medicines using standard oil and those using gutter oil, Yang Sheng, a researcher at the Shanghai Institutes for Biological Sciences under the Chinese Academy of Sciences, told the Global Times Friday, adding that officials should tighten supervision.

While the scandal may hurt consumer confidence in domestic antibiotics, some said the impact will not last long.

"Hospitals are its major buyers of antibiotics, which is not OTC (over-the-counter drugs), and they won't overreact to the news," an industry observer surnamed Zhou said. And firms like Qilu which do not depend on antibiotics for the major part of their income, are unlikely to see big affect on their business either.