Thursday, October 15, 2009

FDA Watching 19 Drugs for Safety Risks

This is an article that very important for everyone to know, especially medical personels.

PLEASE READ THIS !

From Medscape Pharmacists

Susan J. Bliss, RPh, MBA

Published: 10/08/2009

Although prescription drugs undergo clinical trials before they hit the market, unexpected adverse events may still occur in the general patient population. As a result, the Food and Drug Administration (FDA) collects adverse event reports and looks for potential trends. In its latest surveillance report, the agency has identified 19 drugs that are associated with adverse events and, therefore, are undergoing close evaluation.

A centerpiece of the FDA's safety surveillance efforts is the Adverse Drug Event Reporting System. This computerized database is used to collect and analyze safety reports on all approved drug and therapeutic biological products. If a potential safety concern occurs, further epidemiologic studies may be performed, and, eventually, regulatory actions may be taken such as changing a drug's labeling, restricting its use, warning the public, or even removing the drug from the market.[1]

The most recent FDA report based on Adverse Drug Event Reporting System data collected in the fourth quarter of 2008 provides a list of drugs that represents "potential signals of serious risks" or that has new safety information (Table).[2] These potential safety issues were identified in reports filed by clinicians and patients via the agency's MedWatch program.

Table. Drugs With Potentially Serious Risks or New Safety Information

Active Ingredient (Trade Name) or Product Class Potential Safety Risk or New Safety Information
Apomorphine (APOKYN®) Psychiatric events
Choriogonadotropin alfa (Ovidrel®) Anaphylactic reactions
Clomiphene citrate (Clomid®) Visual disorders
Clozapine orally disintegrating tablet (FazaClo®) Deaths
Darifenacin (ENABLEX®) and solifenacin (VESIcare®) Angioedema and other allergic reactions
Drospirenone/ethinyl estradiol (Yasmin®) Pancreatitis
Efavirenz (Sustiva®) Birth defects involving the eye and face
Fibrin sealant, human (Evicel™) Air embolism
Hydrochlorothiazide in combination products Skin reactions
Imiquimod cream (Aldara™) Dysuria due to severe local reactions during use in the genital area
Modafinil (Provigil®) and armodafinil (Nuvigil®) Serious skin reactions
Orlistat (XENICAL®, alli-®) Hepatotoxicity
Polyethylene glycol oral laxative (various trade names) Neuropsychiatric events
Raltegravir (ISENTRESS®) Psychiatric events
Selegiline (EMSAM®) Hypertension
Sumatriptan/naproxen (TREXIMET®) Myocardial infarction
Testosterone gel (AndroGel®, Testim®) Adverse events from accidental exposure
Tolterodine tartrate (Detrol®) Stevens-Johnson syndrome
Varenicline (CHANTIX®) Angioedema, serious skin reactions, visual impairment, accidental injury

From US Department of Health & Human Services, US Food and Drug Administration. Available at: http://www.fda.gov/Drugs/GuidanceComplianceRegulatoryInformation/Surveillance/AdverseDrugEffects/
ucm161063.htm Accessed October 1, 2009.[2]

FDA evaluation of these drugs continues, and officials stress that until a potential relationship between the drug and the risk is fully evaluated, it is not clear what causes the association.[2] The adverse event(s) may be precipitated by concurrent disease states, coadministration of other drugs, change in patient health status, previous drug therapy, or other causes. Clinicians do not need to stop using these drugs, but they should be aware of the potential risks.

Already, the FDA has taken action on several of the drugs on the list. For example:

  • Sumatriptan/naproxen. The FDA reviewed the existing boxed warning on the product label addressing myocardial infarction and concluded it was adequate[2];
  • Testosterone gel. A May 2009 news release announced the addition of a new boxed warning that addresses potential adverse events in children and women who are accidentally exposed to testosterone gel[3]; and
  • Varenicline, bupropion. The FDA distributed a Safety Alert and Public Health Advisory concerning these smoking cessation agents. The FDA now requires that medication guides highlighting the risk of neuropsychiatric symptoms be provided to patients receiving these medications. Information for healthcare professionals, patients, family members, and caregivers is included.[4]

The FDA recently redesigned its Website (www.fda.gov) to make drug safety information more accessible for patients and providers. There are 3 ways to search for topics on this site: an A-to-Z index, a topic index, and a search box.

In addition, the federal agency provides several other tools that are useful for clinicians:

  • MedWatch Website. MedWatch is the agency's reporting program, and the site provides the latest updates on adverse drug event reports. You can use the 1-page MedWatch form to report your own adverse drug events.
  • Drug Safety Newsletter. Designed to complement FDA product labeling, Public Health Advisories, and Alerts for Healthcare Professionals, the Newsletter is available by electronic subscription and is posted on the FDA Website.
  • MedWatch E-list. This free email subscription service allows for rapid dissemination of new safety information regarding drugs and devices. Subscribe here.
  • FDA Transparency Blog. This is a place where you can have a "conversation" with the FDA -- ask questions, respond to their questions, and provide general feedback on the agency's efforts. Regular updates are scheduled to appear through November 2009.

Much of the drug safety information available on the FDA Website can be distributed via RSS feed and text messages sent directly to cell phones. Podcasts, videos, and other newsletters are also available on the Website.

Seasonal Flu Vaccine May Help Protect Against H1N1

Laurie Barclay, MD

October 7, 2009 — Seasonal influenza vaccine may help protect against novel pandemic influenza A (H1N1), according to the results of a frequency-matched, case-control study in Mexico City reported online October 6 in the British Medical Journal. However, the investigators and authors of an accompanying editorial urge that a specific vaccine against H1N1 flu is still needed.

"The viral genomic sequence for several of the novel A/H1N1 strains, including a Mexican isolate, has been made publicly available," write Lourdes Garcia-Garcia, from Instituto Nacional de Salud Pública in Cuernavaca, Mor, Mexico, and colleagues. "Given the new reassortant nature of this virus — that is, unusual mixing of swine, avian, and human influenza genetic sequences — the available evidence, although incomplete, suggests that seasonal vaccines will confer little or no protection against influenza A/H1N1. Mexican guidelines recommend vaccination with trivalent inactivated influenza vaccine (virus strains A/Brisbane/59/2007 (H1N1)-like, A/Brisbane/10/2007 (H3N2)-like, and B/Florida/4/2006-like antigen) for children aged 6-35 months, all adults aged more than 60, and individuals older than 35 months with conditions conferring a higher risk of influenza related complications."

The goal of this study was to examine the association of 2008–2009 seasonal trivalent inactivated vaccine with cases of influenza A/H1N1 during the epidemic in Mexico. From March to May 2009 at a specialty hospital in Mexico City, 60 patients with laboratory-confirmed influenza A/H1N1 were compared with 180 control patients matched for age and socioeconomic status. Control subjects had diseases other than influenza-like illness or pneumonia and were living in Mexico City or the state of Mexico. The primary study endpoints were odds ratio (OR) and effectiveness of trivalent inactivated vaccine against influenza A/H1N1.

Compared with control patients, patients with laboratory-confirmed influenza A (H1N1) had higher rates of hospitalization, invasive mechanical ventilation, and death. However, control patients were more likely than patients with laboratory-confirmed influenza A (H1N1) to have chronic conditions associated with a higher risk for influenza-related complications. H1N1 influenza was independently associated with receipt of trivalent inactivated vaccine (OR, 0.27; 95% confidence interval [CI], 0.11 – 0.66) and with underlying conditions (OR, 0.15; 95% CI, 0.08 – 0.30), based on the multivariate model. Trivalent inactivated vaccine effectiveness against H1N1 influenza was 73% (95% CI, 34% – 89%), and none of the 8 vaccinated patients with laboratory-confirmed influenza A (H1N1) died.

"Preliminary evidence suggests some protection from the 2008-9 trivalent inactivated vaccine against pandemic influenza A/H1N1 2009, particularly severe forms of the disease, diagnosed in a specialty hospital during the influenza epidemic in Mexico City," the study authors write. "These results are to be considered cautiously and in no way indicate that seasonal vaccine should replace vaccination against pandemic influenza A/H1N1 2009. Our data support the hypothesis that partial protection provided by the seasonal vaccine may be explained by the boosting of existing antibodies that were elicited by previous exposure, through either infection or vaccination, to an influenza A/H1N1 virus genetically and antigenically more closely related to the novel influenza virus than contemporary seasonal H1N1 strains."

Limitations of this study include its retrospective design, small sample size, self-reported vaccine status, and lack of blinding of interviewers to the status of patients with laboratory-confirmed influenza A (H1N1) and control patients.

"The estimates for vaccine effectiveness could be inflated owing to a high prevalence of chronic conditions and vaccination in our control population," the study authors conclude. "Similar studies in other settings are needed to confirm or refute our results."

In an accompanying editorial, Menno D. de Jong, from the Academic Medical Centre of the University of Amsterdam, the Netherlands, and Rogier W. Sanders, from Weill Medical College of Cornell University, New York City, also warn that a specific vaccine against influenza A (H1N1) is still needed. Even in countries that have arranged for vaccine production in sufficient quantities, vaccines may not be available in time.

"Antibodies that recognise multiple influenza strains are rare, which explains the frequent lack of cross protection between vaccines and natural infection," Dr. De Jong and Dr. Sanders write. "However, antibodies have been identified that may open possibilities of developing a 'universal flu vaccine.' Traditional flu vaccines have a good track record in terms of efficacy and safety, so it will take years to replace them, but the new techniques and vaccines at various stages of testing are both necessary and promising."

The Mexican Ministry of Health supported this study. Two of the study authors are employed by Laboratorios de Biológicos y Reactivos de México. Dr. De Jong and Dr. Sanders have disclosed no relevant financial relationships.

BMJ. Published online October 6, 2009.

Thursday, October 1, 2009

HOW SHOULD WE MANAGE DRUG INTERACTIONS BETWEEN CLOPIDOGREL AND PROTON-PUMP INHIBITORS?

AN ARTICLE FROM MEDSCAPE

Question

What is the best practice intervention for patients on both clopidogrel and proton-pump inhibitors (PPIs)?

Response from Jenny A. Van Amburgh, PharmD, CDE
Associate Clinical Professor, School of Pharmacy, Northeastern University, Boston, Massachusetts; Director of the Clinical Pharmacy Team and Residency Director, Harbor Health Services, Inc., Boston, Massachusetts

According to a 2007 survey, clopidogrel is the sixth most commonly dispensed medication in the United States. Indicated to reduce the rates of antithrombotic events in patients with a recent cardiovascular event, clopidogrel plays an integral role in the care of patients after myocardial infarction, stroke, or acute coronary syndrome. To reduce the risk for gastrointestinal bleeding, which can be associated with this drug, clinicians often prescribe a concomitant proton-pump inhibitor (PPI) for high-risk patients. Because of its generic availability and over-the-counter (OTC) status, omeprazole (Prilosec®, Prilosec OTC®) is one of the most widely used and accessible PPIs today.

Recent evidence suggests that certain PPIs reduce the antiplatelet effects of clopidogrel. Clopidogrel, a prodrug, requires metabolism in the liver via cytochrome P450 (CYP) enzymes. Once activated, clopidogrel blocks platelet aggregation by inhibiting adenosine diphosphate at the P2Y12 receptor. PPIs, such as omeprazole and its S-enantiomer esomeprazole (Nexium®), are thought to inhibit the CYP2C19 enzyme, thus negating the antithrombotic effects of clopidogrel. CYP2C19 also acts as the primary enzyme responsible for determining a patient’s pharmacodynamic response to clopidogrel. The question of how to best care for patients taking both PPIs and clopidogrel remains unanswered.

Gilard and colleagues conducted a randomized, double-blind, placebo-controlled study to assess the influence of omeprazole on clopidogrel efficacy. They randomly assigned 145 patients who were undergoing coronary artery stent implantation and receiving aspirin, 75 mg daily, and clopidogrel, 75 mg daily (after a 300-mg loading dose), into 2 groups. The treatment group received omeprazole, 20 mg daily for 7 days, and the control group received placebo for 7 days. Assessment of the platelet reactivity index (PRI) was the primary endpoint. A PRI less than 50% indicated a favorable response to clopidogrel.

The data from 124 patients were reviewed after the 7-day course of therapy. Before treatment, the PRI was 83.2% in the control group and 83.9% in the treatment group. At study end, the PRI was 39.8% in the control group and 51.4% in the treatment group (P < .001). Patients who received gastroprotection with omeprazole were 4.31 times more likely to respond poorly to clopidogrel. The long-term implications of this interaction are uncertain but may suggest reduced cardioprotective benefits of clopidogrel.

Although recent evidence indicates an interaction between PPIs and clopidogrel, further emphasis should be placed on the pharmacogenetic properties that influence clopidogrel metabolism. An estimated 30% of whites, 40% of blacks, and over 55% of East Asians have a CYP2C19 gene polymorphism that reduces the pharmacodynamic and pharmacokinetic response of clopidogrel. With clopidogrel metabolism reduced in these patients, concomitant PPI therapy can further reduce its metabolism, predisposing patients to such adverse events as cardiovascular events and death.

At the 2009 Society for Cardiovascular Angiography and Interventions meeting, investigators reported results of a retrospective cohort of over 16,700 patients who received clopidogrel (with or without PPI) after stenting. Patients who received PPIs had a more than 50% higher risk for 1-year cardiovascular events compared with patients who did not receive PPIs. The findings suggest that the increased risk for cardiovascular events may be a class effect of PPIs and may not just be the result of specific agents as once perceived.

For now, healthcare providers should exercise clinical judgment and recommend that only high risk-patients (those receiving dual antiplatelet therapy, those with a history of gastrointestinal bleeding or ulcers, or those receiving concomitant anticoagulant therapy) receive PPIs in conjunction with clopidogrel. The manufacturer of clopidogrel discourages its use with omeprazole on the basis of the new evidence.

If gastroprotection is deemed appropriate, consider using histamine-2 blockers such as ranitidine (Zantac®) or famotidine (Pepcid®) as first-line therapy. Clinicians should note that histamine-2 blockers may be less efficacious than PPIs for gastroprotection, but they have similar efficacy for heartburn and symptoms similar to those of gastroesophageal reflux disease.