ABSTRACT
AIMS: To characterize the impact of potent CYP3A4 inhibition and induction on lapatinib pharmacokinetics. METHODS: Two studies were conducted in healthy subjects. One study examined the effect of ketoconazole 200 mg b.i.d. for 7 days on a single 100-mg dose of lapatinib in 22 healthy subjects. The other study examined the effect of carbamazepine titrated up to 200 mg b.i.d. over 20 days on a single 250-mg dose of lapatinib in 24 healthy subjects. RESULTS: Ketoconazole altered lapatinib AUC, C(max) and half-life, with geometric mean [95% confidence interval (CI)] increases of 3.57-fold (3.07, 4.15), 2.14-fold (1.74, 2.64) and 1.66-fold (1.50, 1.84), respectively, but had no effect on absorption rate. Carbamazepine altered lapatinib AUC, C(max) and absorption rate, with geometric mean (95% CI) decreases of 72% (68, 77), 59% (49, 66) and 28% (4, 46), respectively, but had no effect on half-life. CONCLUSIONS: Systemic exposure to lapatinib was significantly altered by potent inhibition and induction of CYP3A4. Dose adjustments may be required when lapatinib is administered with orally administered drugs that potently alter the activity of this enzyme.
Subject(s)
Antineoplastic Agents/pharmacology , Carbamazepine/administration & dosage , Ketoconazole/administration & dosage , Protein Kinase Inhibitors/pharmacokinetics , Quinazolines/pharmacokinetics , Adolescent , Adult , Analgesics, Non-Narcotic/pharmacology , Antifungal Agents/pharmacology , Area Under Curve , Cross-Over Studies , Drug Interactions , Female , Half-Life , Humans , Lapatinib , Male , Middle Aged , Treatment Outcome , Young AdultABSTRACT
OBJECTIVE: To discuss the role of nonsteroidal antiinflammatory drugs (NSAIDs) in the chemoprevention of colorectal cancer. DATA SOURCES: A MEDLINE search (1966-May 2003) was performed to identify key literature. Search items included, but were not limited to, NSAIDs, colorectal cancer, chemoprevention, cyclooxygenase-2 (COX-2)-specific inhibitors, and familial adenomatous polyposis (FAP). STUDY SELECTION AND DATA EXTRACTION: The search included experimental (in vitro and animal models) and clinical studies evaluating the use of NSAIDs for the chemoprevention of colorectal cancer. The MEDLINE search was supplemented by references from selected articles. DATA SYNTHESIS: Numerous experimental, epidemiologic, and clinical studies suggest that NSAIDs have promise as anticancer agents. The mechanism by which NSAIDs lead to decreased colon carcinogenesis is not fully understood, but may involve restoration of apoptosis and inhibition of prostaglandin-mediated angiogenesis. Compelling evidence from many observational studies has consistently documented a 40-50% reduction in the risk of adenomatous polyps, colorectal cancer incidence, and mortality in patients using NSAIDs. Recent randomized, controlled trials have demonstrated a benefit with aspirin in reducing the rate of development of new or recurrent adenomas in high-risk patients. In addition, randomized studies using sulindac and celecoxib in patients with FAP have documented significant regression of existing adenomatous polyps. CONCLUSIONS: Inhibition of COX-2 is an example of a targeted approach to the chemoprevention of colorectal cancer. However, controversy exists about the safety, efficacy, and optimal treatment regimen of NSAIDs as long-term chemopreventive agents in the general population. Ongoing studies in high-risk patients with both selective and nonselective COX inhibitors will provide important information in the area of colorectal chemoprevention, but clinical trials' use of adenomas as surrogate markers for chemoprevention trials makes their application to the general population limited.
