Biomedical subjects

R P Cheung

Publications and source records attributed to R P Cheung.

4 recordsLinked to original sources

PubMed1987

Effect of hemorrhagic shock on cefazolin and gentamicin pharmacokinetics in dogs.

The physiologic response to traumatic injury may alter the disposition of drugs and thereby affect their therapeutic or toxic potential. A study was conducted in 10 mongrel dogs to determine the effect of experimental hemorrhagic shock with resuscitation on the pharmacokinetics of gentamicin and cefazolin. Single simultaneous intravenous doses of gentamicin (3 mg/kg) and cefazolin (25 mg/kg) were administered to each animal on an initial study day, after which serial blood and urine collections were performed. After 1 week, a standard hemorrhagic shock model was applied to each animal. Shock was continued for 1 h, after which the animal was resuscitated with either whole blood or saline. After stabilization for 20 min, a second dose of gentamicin and cefazolin was administered, and blood and urine were again collected. Drug clearance was not significantly altered, except for that of cefazolin after saline resuscitation, for which there was a significant increase in drug clearance. After both methods of resuscitation an increase in the volume of distribution was noted for cefazolin and gentamicin. Drug half-life was noted to be increased after shock for cefazolin by both resuscitation methods and for gentamicin after shock by saline resuscitation. Although alterations of pharmacokinetic parameters were noted, mean concentrations of gentamicin and cefazolin in serum were similar for pre- and postshock phases.

Animals↗

PubMed1986

Single dose systemic antibiotic prophylaxis of surgical wound infections.

The proper duration of antimicrobial use for the prevention of postoperative surgical infection has been a subject of controversy. Currently, more than 40 published clinical trials are available in which the efficacy of single dose surgical prophylaxis with parenteral antimicrobials has been studied. These studies have compared single doses versus multiple doses of the same agent, single doses of antimicrobial versus placebo, single doses of various antimicrobials, and a single dose of one agent versus multiple doses of another agent. In all trials in which single dose regimens were compared with multidose regimens, the single dose regimens resulted in a similar frequency of postoperative wound infections. Single antimicrobial doses, usually cephalosporins given immediately before operation, are effective in preventing wound infections in gastric, biliary, and transurethral operations, hysterectomies and cesarean sections. For colorectal operations, the value of single parenteral doses of various agents has been established; however, it is not clear if there is an added benefit when oral antimicrobials are also used. For open heart operations or those in which prosthetic materials are implanted, the value of single dose regimens has not been established.

Anti-Bacterial Agents↗

PubMedDate not supplied

Investigation of mezlocillin disposition with a porcine model.

The suitability of the pig as an animal model for mezlocillin disposition was assessed. Serum, urine, and bile were collected after the administration of 50, 100 and 200 mg kg-1 mezlocillin to pigs and drug pharmacokinetics were characterized. Mezlocillin concentrations in biological fluids were determined by HPLC and free mezlocillin was determined by ultrafiltration. The pharmacokinetics of mezlocillin appeared to be independent of dose over the dosage range studied. Total clearance, renal clearance, and biliary clearance were 0.18 (0.05) 1 h-1 kg-1, 0.13 (0.03) 1 h-1 kg-1, and 0.07 (0.02) 1 h-1 kg-1, respectively. The steady-state volume of distribution was 0.29 (0.08) 1 kg-1. The pharmacokinetic parameters determined in the porcine model are similar to those reported for health human volunteers. Therefore, this model appears suitable for the study of mezlocillin disposition, and may be applied to the study of other agents that are appreciably biliary excreted.

Animals↗

PubMedDate not supplied

Vancomycin: an update.

Vancomycin is a narrow-spectrum glycopeptide antibiotic with potent antistaphylococcal activity. It is primarily active against gram-positive organisms. Bacterial resistance rarely develops due to its numerous modes of action. The toxic potential of vancomycin is less significant than previously thought. "Red neck syndrome" seems to be the most common side effect and appears to be caused by rapid intravenous infusion. It is characterized by erythema at the base of the neck and the upper back; hypotensive episodes may also occur. Nephrotoxicity and ototoxicity are rare. Relationships between toxicities and serum concentrations have not been established. The disposition of vancomycin after intravenous administration proceeds biphasically--rapid distribution followed by elimination. The drug is excreted primarily unchanged in the urine by glomerular filtration. Vancomycin clearance is reduced and elimination half-life is prolonged in patients with renal insufficiency. Various methods have been published to aid in dosing the drug in these patients. Vancomycin is the drug of choice in the treatment of methicillin-resistant staphylococcal infections. It is also useful in the treatment of gram-positive endocarditis and has been used as alternative therapy in the treatment of prophylaxis of gram-positive infections in penicillin-allergic patients. Oral vancomycin is the preferred therapy in antibiotic-associated colitis.

Absorption↗