Updated from 2:39 p.m. EDT

Shares of aaiPharma ( AAII) were among the best-performing health and pharmaceutical stocks Monday, rising 34.1% after the company announced that it made a belated interest payment that was due Oct. 1, and it restructured its debt.

Late Friday, the drug company said that it received the requisite consents to adopt amendments required for its senior credit facility. As part of the restructuring, the senior debt amendment increased the amount of term loans available to aaiPharma by up to $30 million. The company tapped $20 million of these new loans to make a $10 million interest payment that was due Oct. 1. The remaining portion, the company said, is being used for working-capital purposes. Shares traded up 99 cents to $3.89.

Nastech Pharmaceutical ( NSTK) rose 1.4% after the company received an approvable letter from the Food and Drug Administration for its nasal spray that's used for the treatment of vitamin B-12 deficiency. Before final product approval, the FDA must inspect Nastech's B-12 raw material manufacturing facility and finalization of the labeling must be completed. There were no other FDA requirements that would prevent the company from receiving final approval. Shares traded up 18 cents to $13.33.

Shares of AVI BioPharma ( AVII) rose 4% after the company reported positive results from experiments testing the effect of its antisense drugs against the Ebola virus in vivo. The testing, which was conducted in collaboration with AVI, the U.S. Army Medical Research Institute of Infectious Diseases, and labs in Germany, showed that AVI's Neugene antisense drugs "may be a viable component of the country's biodefense strategy," the company said. The results were strong enough to convince the Army Medical Research Institute of Infectious Diseases to expand the research program. Shares traded up 9 cents to $2.34.

Kinetic Concepts ( KCI) rose 11.7% after the company posted third-quarter results that easily outpaced estimates. The maker of medical equipment posted earnings of 46 cents a share on sales of $257.2 million. Analysts polled by Thomson First Call were expecting earnings of 39 cents a share on sales of $249 million. Looking ahead, the company forecast full-year pro forma earnings of $1.61 to $1.67 a share on sales of $985 million to $995 million. Analysts had been expecting earnings of $1.53 on sales of $977.6 million. Shares traded up $5.82 to $55.65.

Other health care volume movers included StemCells ( STEM), up 57 cents to $4.28; Merck ( MRK), down $3.03 to $28.28; Pfizer ( PFE), down 15 cents to $28.80; Aastrom Biosciences ( ASTM), up 16 cents to $1.36; and Amgen ( AMGN), down $1.13 to $55.67.