Show #54, August 2006
Show #54, August 2006
|FDA Approves HPV and Shingles Vaccines|
FDA recently approved two new vaccines manufactured by Merck and Co. The first one, called Gardasil, prevents cervical cancer, precancerous genital lesions and genital warts caused by human papillomavirus (HPV).
Gardasil is effective against four types of HPV: types 16 and 18, which cause about 70% of cervical cancers, and types 6 and 11, which cause about 90% of genital warts. Gardasil is approved for use in girls and women aged 9 to 26. Merck is currently studying the safety and effectiveness of the vaccine in males.
In clinical studies conducted in 21,000 women, Gardasil was nearly 100% effective in preventing HPV disease for the four virus types covered by the vaccine. Of course, the vaccine won't protect a woman against a type of HPV that isn't in the vaccine, and it won't work as a treatment against HPV. For those reasons, and because no vaccine is 100 % effective, routine Pap screening is still recommended.
Merck's other vaccine, called Zostavax, is used to reduce the risk of shingles in people 60 and older.
Shingles is caused by a reactivation of the varicella zoster, or chickenpox, virus. It can occur at any age, but it is most common in people over 60, and the risk increases as people get older.
In clinical studies conducted in approximately 38,000 people, the vaccine reduced the overall occurrence of shingles by about 50%. The vaccine's effectiveness was 64% in people between the ages 60-69, but it declined with increasing age to 41% for those in their 70's, and 18% for those 80 and older.
Zostavax should not be used in people who are allergic to neomycin or any component of the vaccine. And since Zostavax is a live attenuated vaccine, it should not be given to people who have weakened immune systems or to women who are or may be pregnant. Zostavax should also not be used in children and it is not a substitute for Varivax, the vaccine used to prevent chicken pox.
- Product Approval Information - Licensing Action - Quadrivalent Human Papillomavirus (Types 6, 11, 16, 18) Recombinant Vaccine - GARDASIL.
- Product Approval Information - Licensing Action - Zoster Vaccine, Live, (Oka/Merck) - Zostavax.
- CDC MMWR. Quadrivalent Human Papillomavirus Vaccine: Recommendations of the Advisory Committee on Immunization Practices (ACIP). March 12, 2007.
|New Drug Approved for Parkinson’s Disease|
FDA recently approved a new drug to treat Parkinson's disease, called Azilect (rasagiline). Azilect is an MAO type-B inhibitor that blocks the breakdown of dopamine in the brain. Azilect was approved as a single therapy for treating early Parkinson's disease, and also in combination with levodopa in treating advanced cases.
As with many other MAO inhibitors, patients taking Azilect must avoid foods rich in tyramine such as aged cheese and red wine, and also medications containing amines, including many cough and cold remedies. Combining Azilect with these substances can trigger a hypertensive crisis which could be fatal.
Like most other medications for Parkinson's, Azilect can cause dyskinesias, hallucinations and hypotension. Azalect is contraindicated in combination with several other drugs, including dextromethorphan, meperidine and other analgesics.
Melanoma has been diagnosed in a small number of patients treated with Azilect. Parkinson's disease itself appears to increase the risk of melanoma, so it's not known at present whether the drug further increases the risk. The manufacturer will perform a postmarket study to address this question. In the meantime, the product labeling will recommend that patients undergo periodic dermatologic examinations.
|Caution on use of ACE inhibitors in First Trimester|
A recent study in the New England Journal of Medicine suggests that ACE inhibitors, which are widely used to treat hypertension, may be associated with an increased risk of major congenital malformations when used by women during the first trimester of pregnancy.
The labeling for ACE inhibitors already states that these drugs can produce major congenital malformations, but that precaution is aimed at preventing harm to the fetus during the second and third trimesters of pregnancy. This new study focuses on the first trimester, a time when neither the woman nor her doctor may realize that she's pregnant.
This one study does not establish a causal relationship between ACE inhibitors and birth defects, but it does raise some reason for concern. So FDA is recommending is that ACE inhibitors be prescribed for pregnant women only if the expected benefit clearly exceeds the potential risk. If a woman becomes pregnant while she is on an ACE inhibitor, the recommendation is to change to a different drug as soon as possible.
Women who are taking these drugs, or a combination product containing ACE inhibitors, to tell their practitioner if they're planning a pregnancy or think they might be pregnant. And they should be counseled about the potential risks throughout pregnancy, especially during the second and third trimesters.
ACE inhibitor drugs include: Lotensin (benazepril), Capoten (captopril), Vasotec oral and injectable (enalapril/enalaprilat), Monopril (fosinopril), Zestril (lisinopril), Prinivil (lisinopril), Univasc (moexipril), Aceon (perindopril), Accupril (quinapril), Altace (ramipril), Mavik (trandolapril)
ACE inhibitors combined with other antihypertensive drugs include: Capozide (captopril/hydrochlorothiazide), Lotrel (benazepril, amlodipine), Vaseretic (enalopril/hydrochlorothiazide), Prinzide (lisinopril/ hydrochlorothiazide), Accuretic (Accupril/ hydrochlorothiazide)
- FDA MedWatch Safety Alert 2006 - Angiotensin-converting enzyme inhibitors (ACE inhibitors) drug class. June 7, 2006.
|Caution on Gadolinium-Containing Contrast Agents in Patients with Renal Failure|
FDA has learned of a rare, possibly fatal disease among patients with renal failure who underwent Magnetic Resonance Angiography (MRA) using Omniscan, a contrast agent containing gadolinium. The disease is called Nephrogenic Systemic Fibrosis/ Nephrogenic Fibrosing Dermopathy (NSF/NFD). To date, NSF/NFD has been found almost exclusively in patients with renal failure. The disease is characterized by fibrosis of the skin and connective tissues.
Five gadolinium-containing contrast agents have been approved in the U.S. for use with MRI. However, none have been approved for MRA, where the doses are up to three times higher than for MRI. But these agents have been used off-label for MRA.
At this point a causal relationship between gadolinium-containing contrast agents and NSF/NFD has not been established. FDA is investigating the reports received so far, other data bases and the medical literature to try to answer this question. In the meantime, FDA says that physicians should be cautious about using gadolinium-containing contrast agents in patients with advanced renal failure.
Although there are no data to determine the utility of dialysis to prevent or treat NSF/NSD in patients with decreased kidney function, there is evidence that dialysis can accelerate the excretion of gadolinium. So it may be prudent to institute prompt dialysis in patients with advanced kidney dysfunction who receive a gadolinium contrast MRA.
Patients should be aware of the signs and symptoms and report these to their health professional. These include swelling and tightening of the skin, and difficulty in flexing or extending the joints. Cases of NSF/NFD that may be related to gadolinium-containing contrast agents should be reported through the MedWatch system.
- FDA MedWatch Safety Alert 2006 - Gadolinium-containing Contrast Agents for Magnetic Resonance Imaging (MRI): Omniscan, OptiMARK, Magnevist, ProHance, and MultiHance. June 8, 2006.
- MedWatch Voluntary Reporting by Health Care Professionals.
|Severe Bone and Muscle Pain with Bisphosphonates|
A recent FDA article describes severe pain associated with two bisphosphonate drugs: Fosamax (alendronate sodium) and Actonel (risedronate sodium).
The article, which was published in the Archives of Internal Medicine, describes over a hundred reports received by the FDA of severe bone, joint and muscle pain in patients being treated with Fosamax for osteoporosis. Many patients were unable to walk, climb stairs, or perform usual activities, and some of them became bedridden. Many of them had numerous diagnostic tests with mostly normal findings.
A majority of the patients experienced relief from pain after the drug was discontinued. This improvement was gradual in most of the patients, although some did show immediate improvement.
The article also notes that the FDA has received similar reports for Actonel, another bisphosphonate drug, and this suggests a possible class effect for these drugs.
The article says that pain in patients treated with bisphosphonates is likely to be underreported because of its subjective nature and because physicians may attribute the pain to the osteoporosis itself. It concludes that patients should be instructed to report severe bone, joint, or muscle pain that starts shortly after beginning bisphosphonate therapy, and that physicians should consider discontinuing the drug if that happens.
|USP Statement on Preventing Errors with Neuromuscular Blocking Agents|
In a previous show, we told you about a report from the Institute for Safe Medication Practices (ISMP) which warned about inadvertently giving neuromuscular blocking agents such as pancuronium to patients who aren't receiving ventilator support. This can cause respiratory arrest, permanent injury, or death.
ISMP noted that some errors are due to look-alike packaging and labeling, and recommended placing warning labels on vials, syringes, infusion bags and boxes that say "Warning: paralyzing agent, causes respiratory arrest." ISMP also cited unsafe storage as a cause of errors, and they recommended keeping boxes containing these agents in separate refrigerators and shelves.
ISMP had several other recommendations. For example, allow floor stock of these drugs only in the OR, ED and critical care units, require an independent double check of the drug against the actual order before dispensing and administering, and isolate vials, syringes and infusion bags containing the drug as soon as the patient has been extubated or the drug discontinued.
Now the United States Pharmacopeia (USP) has issued a similar statement warning about these kinds of errors. The USP report lists over 20 recommendations to help solve this problem. Here are a few of them:
• When choosing neuromuscular blocking agents for purchase, select those that have distinctive labeling and packaging.
• Use sealed intubation kits or anesthesia kits in areas outside the OR, which will restrict access until an intubation procedure has begun.
• Except for placing an endotracheal tube, don't administer neuromuscular blocking agents in a critical care setting without medicating the patient for pain or anxiety, even without obvious symptoms or signs.
• Limit orders for these blocking agents to the duration of mechanical ventilation.
• Automatically discontinue all orders for neuromuscular blocking agents when the patient is transferred out of the critical care area. You can see all of the USP recommendations on our web site.
- Improving the safety of neuromuscular blocking agents: A statement from the USP Safe Medication Use Expert Committee. Am J Health-Syst Pharm. 2006. 63:139-42.
|Preventing Errors with Tablet Splitting|
Splitting tablets is a common practice where tablets of a higher strength than the patient needs are broken in half, or even quarters, to provide the correct dose. This is often done to reduce costs, since the higher strength tablet sometimes costs about the same as the lower strength one. In some cases the hospital may not stock the lower strength of a particular medication, and in other cases the patient may not be able to swallow a whole tablet.
But unless certain precautions are taken, tablet splitting can lead to medication errors. If the patient is splitting the tablets at home, he or she can become confused about the dose. Patients often forget to split their tablets, or they can split them again after they've been pre-split in the pharmacy. Some patients may not have the visual acuity or motor skill to do the splitting properly. Even when split well, the pieces can crumble or be uneven in size.
Patients may not be the only possible source of error. When the prescription is written as "1/2 tablet," the pharmacist can confuse this with "1-2 tablets," which could lead to a fourfold overdose.
ISMP suggests several ways to prevent errors with tablet splitting:
• Be sure that the tablet in question is suitable for splitting. If in doubt, check with the manufacturer.
• Ensure the patient has the understanding, skill and motivation to split the tablets. You may have to enlist a family member or caretaker to do this.
• If the tablets are to be split at home, provide the patient or family with a tablet splitter to improve accuracy.
• For inpatients, the pharmacy staff should dispense the tablets already split, rather than relying on nurses to do this on the floor.
• Prescribers should order the strength in milligrams when possible, to avoid misreading an order for "1/2 tablet" for "1-2 tablets."
- ISMP Medication Safety Alert. Tablet Splitting: Do it only if you "half" to and then do it safely. May 18, 2006.
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