Digestive Health Newsletter

Virtual Colonoscopy

Brooks D. Cash, MD, FACG, AGAF

March 02, 2012

Introduction

March is National Colorectal Cancer Awareness Month, making this a good time to think about whether you're due for a screening colonoscopy. If you have inflammatory bowel disease (IBD), you are probably very familiar with conventional colonoscopy, which is discussed in The Scoop on the Scope. This issue of the newsletter will focus on virtual colonoscopy. Like conventional colonoscopy, it can also be used to detect polyps (precancerous growths), cancer, and other diseases of the large intestine.

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What is virtual colonoscopy?

The technical name for virtual colonoscopy is computerized tomographic (CT) colonography. Virtual colonoscopy uses a CT scanner to noninvasively create images of your colon.

During the procedure, which takes only about 5 minutes, you lie on a table that will move through the scanner. First, you are positioned on your left side with your knees bent up toward your chest. A short tube is inserted into your rectum and carbon dioxide gas is pumped into your colon until it is expanded. It's then time for the scan. You start out on your back and then on your stomach, while hundreds of cross-sectional CT images are obtained. A computer combines the images to create a 2- or 3-dimensional view of your colon. During the procedure, you will be asked to hold your breath for short (15- to 30-second) periods of time.

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How is it different from conventional colonoscopy?

Conventional colonoscopy is typically performed in a doctor's office or hospital outpatient clinic and uses a long, lighted, flexible tube connected to a camera and a video display monitor, whereas virtual colonoscopy is performed in the radiology department of a medical center, hospital, or imaging center using CT equipment. Because virtual colonoscopy is less invasive than conventional colonoscopy, there are lower risks of bleeding or perforation (a tear in the colon).1 It is also a relatively faster procedure and does not require sedation. However, if polyps are detected, a follow-up conventional colonoscopy will be required to remove them. If results are normal (ie, no polyps or other disease), a virtual colonoscopy should be repeated every 5 years, whereas a conventional colonoscopy should be repeated every 10 years (although if you've had IBD for 8 to 10 years, your doctor will probably recommend that you schedule a colonoscopy every 1 to 2 years).

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How do I prepare for it?

Preparing for a virtual colonoscopy is very similar to preparing for a conventional colonoscopy. Clinic staff will provide you with instructions regarding a bowel preparation regimen, and it is important to tell them about any medications you are taking. Following bowel preparation, you will need to drink a small amount of liquid called contrast media, which will allow any remaining colon contents to be "tagged" for digital subtraction by the computer.

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Is it painful?

Expanding your colon with gas, which is required for either virtual or conventional colonoscopy, can be uncomfortable and cause cramping. However, in a recent study of patients undergoing virtual colonoscopy, less than 3% reported discomfort that was more than "moderate," and more than 10% of patients reported absolutely no discomfort.2 Among the patients who reported discomfort, only 8% described it as "pain," and less than 1% described the discomfort as persisting beyond the duration of the exam.

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What happens after the test?

Following your virtual colonoscopy, a radiologist will examine the results and generate a report for your doctor. If polyps are detected, conventional colonoscopy will be required to remove them. If the practice performing your virtual colonoscopy is integrated with a gastroenterology practice and endoscopy suite, the procedure can sometimes be scheduled for the same day so that you don't have to repeat the bowel prep. Only about 12% of healthy patients require subsequent conventional colonoscopy and polyp removal, although in older patients this increases to
20% to 25%.3

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How accurate is it?

A number of studies have reported that virtual colonoscopy is at least as sensitive as conventional colonoscopy for the detection of polyps that are at least 10 mm (which constitute 10% of all colorectal polyps and are the most important predictors of cancer). It is 80% to 90% sensitive for polyps ranging from 6 mm to 9 mm and is unreliable for polyps smaller than 6 mm (which constitute 80% of all polyps and are very unlikely to harbor cancer).4-6

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Is it covered by insurance?

On average and without insurance, virtual colonoscopy costs $400 to $800 and conventional colonoscopy costs $1500 to $3000.7,8 The Blue Cross and Blue Shield Technology Evaluation Center determined that virtual colonoscopy meets criteria to be considered an effective colon cancer screening test, and a number of other major health insurers cover the procedure. Policies differ, however, so be sure to check with your health insurance provider to confirm your options.

On the other hand, Medicare does not yet cover virtual colonoscopy. The Centers for Medicare and Medicaid Services last evaluated the procedure 3 years ago and considered it a "new and emerging technology" that required additional evidence prior to their decision to cover the costs of the test for Medicare patients.

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What are the advantages and disadvantages?

Virtual colonoscopy has a number of advantages over conventional colonoscopy. It is a less invasive procedure that takes less time and has a lower risk of complications.1 Because no sedation is required, you can drive yourself home and/or return immediately to work. Occasionally, virtual colonoscopy identifies a significant abnormality outside of the colon that would otherwise have gone undetected.9,10 In a recent study, patients who had experienced both conventional and virtual colonoscopy preferred the latter by a margin of 5.5 to 1, and when asked about plans for future screening, patients reported they would choose virtual colonoscopy over conventional colonoscopy at a rate of nearly 8 to 1.2

However, virtual colonoscopy also has its disadvantages. Unlike conventional colonoscopy, the procedure requires additional follow-up to remove polyps if they are detected, and if the follow-up occurs on a subsequent day, the bowel preparation must be repeated. There is also a risk of missing small polyps that could develop into cancer. Virtual colonoscopy is not meant to be anything other than a colorectal cancer screening test. It does not permit direct visual examination of the lining of the colon like conventional colonoscopy does. Finally, Medicare and some health insurance plans do not cover the procedure, and the risk of radiation exposure remains uncertain, although it is significantly lower radiation than one is exposed to during standard CT scans.

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Are there instances when I should not undergo virtual colonoscopy?

Pregnant women and children should not undergo virtual colonoscopy, and the procedure should not be used for routine IBD follow-up or evaluation of anal canal disease. Other contraindications include symptomatic acute colitis, acute diarrhea, recent acute diverticulitis, recent colorectal surgery or polyp removal, a symptomatic colon-containing abdominal wall hernia, known or suspected colonic perforation, and symptomatic or high-grade small bowel obstruction.

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Conclusion

Approximately 1 in 18 Americans will develop colorectal cancer during their lifetime, and IBD increases your risk.11,12 But the good news is that, if detected early, colorectal cancer is one of the most treatable cancers.13 What's more, screening can even help prevent it. Virtual colonoscopy is one of the many procedures that can be used to screen for colon cancer. During National Colorectal Cancer Awareness Month, talk to your doctor about which test is best for you.

References

1. Atalla MA, Rozen WM, Niewiadomski OD, Croxford MA, Cheung W, Ho YH. Risk factors for colonic perforation after screening computed tomographic colonography: a multicentre analysis and review of the literature. J Med Screen. 2010;17:99-102. 2. Pooler BD, Baumel MJ, Cash BD, et al. Screening CT colonography: multicenter survey of patient experience, preference, and potential impact on adherence. AJR Am J Roentgenol. In press. 3. Virtual colonoscopy: frequently asked questions about CT colonography. American College of Gastroenterology website. http://s3.gi.org/patients/ccrk/VCFAQ.pdf. Accessed February 23, 2012. 4. Chaparro M, Gisbert JP, Del Campo L, Cantero J, Maté J. Accuracy of computed tomographic colonography for the detection of polyps and colorectal tumors: a systematic review and meta-analysis. Digestion. 2009;80:1-17. 5. Pickhardt PJ, Choi JR, Hwang I, et al. Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. N Engl J Med. 2003;349:2191-2200.
6. Cash B, Riddle MS, Bhattacharya I, et al. Observed outcomes with computerized tomographic colonography in a medicare-aged population: an analysis of over 1,400 patients. AJR Am J Roentgenol. In press. 7. Gut check: compare the choices that work. US Department of Health and Human Services website. http://gutcheck.nci.nih.gov/screenings/index.html. Accessed February 23, 2012. 8. Gut check: virtual colonoscopy. US Department of Health and Human Services website. http://gutcheck.nci.nih.gov/screenings/virtual-colonoscopy/index.html. Accessed February 23, 2012. 9. US Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2008;149:627-637. 10. Whitlock EP, Lin JS, Liles E, Beil TL, Fu R. Screening for colorectal cancer: a targeted, updated systematic review for the US Preventive Services Task Force. Ann Intern Med. 2008;149:638-658. 11. Ahuja N, Li Q, Mohan AL, Baylin SB, Issa JP. Aging and DNA methylation in colorectal mucosa and cancer. Cancer Res. 1998;58:5489-5494. 12. Potack J, Itzkowitz SH. Colorectal cancer in inflammatory bowel disease. Gut Liver. 2008;2:61-73. 13. Brooks D. Never tested for colon cancer? What's your excuse? American Cancer Society website. http://www.cancer.org/cancer/news/expertvoices/
post/2011/03/09/never-tested-for-colon-cancer-whats-your-excuse.aspx. Published March 9, 2011. Accessed February 29, 2012.

The next issue of Your Digestive Health will focus on financial challenges related to chronic illness.

About the author
Brooks D. Cash, MD, FACG, AGAF

Brooks D. Cash, MD, FACG, AGAF

Dr Cash is the Chief of Medicine at the Walter Reed National Military Medical Center in Bethesda, MD. Board certified in gastroenterology, his research has had an emphasis on functional gastrointestinal disorders, colon cancer screening with colonoscopy and CT colonography, Barrett's esophagus, and outcomes research.
Dr Cash is a professor of medicine at the Uniformed Services University of the Health Sciences in Bethesda, MD.

About the author
Brooks D. Cash, MD, FACG, AGAF

Brooks D. Cash, MD, FACG, AGAF

Dr Cash is the Chief of Medicine at the Walter Reed National Military Medical Center in Bethesda, MD. Board certified in gastroenterology, his research has had an emphasis on functional gastrointestinal disorders, colon cancer screening with colonoscopy and CT colonography, Barrett's esophagus, and outcomes research.
Dr Cash is a professor of medicine at the Uniformed Services University of the Health Sciences in Bethesda, MD.

About the author
Brooks D. Cash, MD, FACG, AGAF

Brooks D. Cash, MD, FACG, AGAF

Dr Cash is the Chief of Medicine at the Walter Reed National Military Medical Center in Bethesda, MD. Board certified in gastroenterology, his research has had an emphasis on functional gastrointestinal disorders, colon cancer screening with colonoscopy and CT colonography, Barrett's esophagus, and outcomes research.
Dr Cash is a professor of medicine at the Uniformed Services University of the Health Sciences in Bethesda, MD.

Important Safety Information about AZASAN

WARNING: Chronic immunosuppression with this purine antimetabolite increases risk of malignancy in humans. Reports of malignancy include post-transplant lymphoma and hepatosplenic T-cell lymphoma (HSTCL) in patients with inflammatory bowel disease. Physicians using this drug should be very familiar with this risk as well as with the mutagenic potential to both men and women and with possible hematologic toxicities. Physicians should inform patients of the risk of malignancy with AZASAN. See WARNINGS.

AZASANAZASAN® (azathioprine tablets) 75/100 mg is indicated as an adjunct for the prevention of rejection in renal homotransplantations, and also for the management of active rheumatoid arthritis to reduce signs and symptoms. Patients are at increased risk of developing lymphoma and other malignancies, particularly of the skin. Exposure to sunlight and ultraviolet light should be limited by wearing protective clothing and a high SPF sunscreen. Patients should have complete blood count (CBC), including platelet counts periodically during treatment. TPMT testing should be conducted to identify with absent or reduced TPMT activity. The most commonly reported side effects associated with AZASAN therapy are leukopenia and/or thrombocytopenia, secondary infections, neoplasia, nausea, vomiting, diarrhea, fever, myalgias, skin rashes, and hepatotoxicity. AZASAN therapy should be given cautiously when used concomitantly with allopurinol, ACE inhibitors, and other agents affecting myelopoiesis. Patients with rheumatoid arthritis previously treated with alkylating agents (cyclophosphamide, chlorambucil, melphalan, or others) may have a prohibitive risk of malignancy if treated with AZASAN. AZASAN is contraindicated in pregnant and lactating women and in patients who have shown hypersensitivity to this product.

Consult with your physician to see if this product is right for you.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch/ or call 1-800-FDA-1088.

For product information, adverse event reports, and product complaint reports, please contact:

Salix Product Information Call Center
Phone: 1-800-508-0024
Fax: 1-510-595-8183
Email: salix@medcomsol.com

Please see complete Prescribing Information for AZASAN, including BOXED WARNING.pdf

Indication for METOZOLV ODT

METOZOLV® ODT is indicated for short-term (4 to 12 weeks) therapy for adults with symptomatic, documented gastroesophageal reflux disease that fails to respond to conventional therapy (refractory GERD) and for the relief of symptoms associated with acute and recurrent diabetic gastroparesis (gastric stasis) in adults.

Important Safety Information about METOZOLV ODT

WARNING: TARDIVE DYSKINESIA

See full prescribing information for complete boxed warning.

Treatment with metoclopramide can cause tardive dyskinesia, a serious movement disorder that is often irreversible. The risk of developing tardive dyskinesia increases with the duration of treatment and the total cumulative dose.

Metoclopramide therapy should be discontinued in patients who develop signs or symptoms of tardive dyskinesia. There is no known treatment for tardive dyskinesia. In some patients, symptoms may lessen or resolve after metoclopramide treatment is stopped.

Treatment with metoclopramide for longer than 12 weeks should be avoided in all but rare cases where therapeutic benefit is thought to outweigh the risk of developing tardive dyskinesia.

Do not take METOZOLV ODT (metoclopramide hydrochloride) if you have stomach or intestine problems that could get worse with METOZOLV ODT, such as bleeding, blockage or a tear in your stomach or bowel wall; have an adrenal tumor called pheochromocytoma; are allergic to metoclopramide or any of the ingredients in METOZOLV ODT; take medicines that can cause uncontrolled movements, such as medicines for mental illness; or have seizures. 

METOZOLV ODT can cause serious side effects, including:
Tardive dyskinesia (abnormal muscle movements): these movements happen mostly in the face muscles. You cannot control these movements. They may not go away even after stopping METOZOLV ODT. There is no treatment for tardive dyskinesia, but symptoms may lessen or go away over time after you stop taking METOZOLV ODT.

Uncontrolled spasms of your face and neck muscles, or muscles of your body, arms, and legs (dystonia): these muscle spasms can cause abnormal movements and body positions. These spasms usually start within the first 2 days of treatment. These spasms happen more often in children and adults younger than 30.

Parkinsonism: symptoms include slight shaking, body stiffness, trouble moving or keeping your balance. If you have Parkinson’s Disease, your symptoms may become worse while you are taking METOZOLV ODT.

Neuroleptic Malignant Syndrome (NMS): NMS is a rare but very serious condition that can happen with METOZOLV ODT. NMS can cause death and must be treated in a hospital. Symptoms of NMS include: high fever, stiff muscles, problems thinking, very fast or uneven heartbeat, and increased sweating.

Depression, thoughts about suicide, and suicide: some people who take METOZOLV ODT may become depressed. You may have thoughts about hurting or killing yourself. Some people who have taken metoclopramide products have ended their own lives (suicide).

High blood pressure: METOZOLV ODT can cause your blood pressure to increase.

Too much body water: people who have certain liver problems or heart failure and take METOZOLV ODT may hold too much water in their body (fluid retention). Tell your doctor right away if you have sudden weight gain, or swelling of your hands, legs, or feet.

Symptoms from stopping (withdrawal) METOZOLV ODT: you may still have side effects after you stop METOZOLV ODT such as headaches, and feeling dizzy or nervous.

METOZOLV ODT comes as a tablet that melts in your mouth.  Take METOZOLV ODT exactly as prescribed by your doctor. Do not change your dose unless your doctor tells you to.  You should not take METOZOLV ODT for more than 12 weeks. Take METOZOLV ODT at least 30 minutes before eating and at bedtime. 

It is not known if METOZOLV ODT is safe or works in children.

The elderly may be at greater risk for sleepiness and movement disorders with METOZOLV ODT.

If you have kidney problems, speak with your healthcare provider before taking METOZOLV ODT.

The most common side effects of METOZOLV ODT are:  headache, nausea, vomiting, tiredness, and sleepiness. You may have more side effects the longer you take METOZOLV ODT and the more you take. Tell your doctor about any side effects that bother you or do not go away. These are not all the possible side effects of METOZOLV ODT.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch/ or call 1-800-FDA-1088.

For product information, adverse event reports, and product complaint reports, please contact:

Salix Product Information Call Center
Phone: 1-800-508-0024
Fax: 1-510-595-8183
Email: salix@medcomsol.com

Please see complete Prescribing Information for METOZOLV ODT, including BOXED WARNING.pdf

Indication for OSMOPREP

OSMOPREP® (sodium phosphate monobasic monohydrate, USP, and sodium phosphate dibasic anhydrous, USP) Tablets are indicated for cleansing of the colon as a preparation for colonoscopy in adults 18 years of age or older.

Important Safety Information about OSMOPREP

WARNINGS

There have been rare, but serious reports of acute phosphate nephropathy in patients who received oral sodium phosphate products for colon cleansing prior to colonoscopy. Some cases have resulted in permanent impairment of renal function and some patients required long–term dialysis. While some cases have occurred in patients without identifiable risk factors, patients at increased risk of acute phosphate nephropathy may include those with increased age, hypovolemia, increased bowel transit time (such as bowel obstruction), active colitis, or baseline kidney disease, and those using medicines that affect renal perfusion or function (such as diuretics, angiotensin converting enzyme [ACE] inhibitors, angiotensin receptor blockers [ARBs], and possibly nonsteroidal anti–inflammatory drugs [NSAIDs]).

It is important to use the dose and dosing regimen as recommended (PM/AM split dose).

Do not take OSMOPREP® (sodium phosphate monobasic monohydrate, USP, and sodium phosphate dibasic anhydrous, USP) if you have had a kidney biopsy that shows you have kidney problems because of too much phosphate, a blockage of your intestines, had stomach surgery involving stapling or bypass, a hole or opening in your intestines, significant irritation of the bowels such as toxic megacolon or toxic colitis, or you are allergic to sodium phosphate salts or any of the ingredients in OSMOPREP.

Rare, but serious kidney problems can happen in people who take medicines made with sodium phosphate, including OSMOPREP, to clean the colon before colonoscopy. These kidney problems can sometimes lead to kidney failure or the need for dialysis. These problems occur within a few days, but may develop several months after taking OSMOPREP.

Conditions that can make you more at risk for having serious kidney problems with OSMOPREP include: the loss of too much body fluid (dehydration), slow moving bowels, bowels blocked with stool (constipation), severe stomach pain or bloating, any disease that causes bowel inflammation (colitis), kidney disease or kidney problems, heart failure, and the use of water pills or non‐steroidal anti‐inflammatory drugs (NSAIDS). Your age may also affect your risk for having kidney problems with OSMOPREP. Talk to your doctor before you start to take OSMOPREP.

If you have a history of seizures or are at risk for seizures due to certain medications (such as tricyclic antidepressants), are undergoing withdrawal from alcohol or benzodiazepines, or if you have hyponatremia, you should talk to your doctor before you take OSMOPREP.

If you have been told you are at high risk for developing an arrhythmias or irregular heartbeat, you should tell your doctor.

It is important to drink sufficient liquids before, during, and after use of OSMOPREP.

If you have had an inflammatory bowel disease diagnosis or a blockage/opening of your intestines, tell your doctor before taking OSMOPREP.

If you are pregnant, planning to become pregnant, or nursing, talk to your healthcare provider before taking OSMOPREP.

In clinical trials, the most common side effects occurring in at least 3% of adult patients taking OSMOPREP were bloating, abdominal (stomach) pain, nausea, and vomiting.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch/ or call 1-800-FDA-1088.

For product information, adverse event reports, and product complaint reports, please contact:

Salix Product Information Call Center
Phone: 1-800-508-0024
Fax: 1-510-595-8183
Email: salix@medcomsol.com

Please see complete Prescribing Information for OSMOPREP, including BOXED WARNING.

Indication for OSMOPREP

OSMOPREP® (sodium phosphate monobasic monohydrate, USP, and sodium phosphate dibasic anhydrous, USP) Tablets are indicated for cleansing of the colon as a preparation for colonoscopy in adults 18 years of age or older.

Important Safety Information about OSMOPREP

WARNINGS

There have been rare, but serious reports of acute phosphate nephropathy in patients who received oral sodium phosphate products for colon cleansing prior to colonoscopy. Some cases have resulted in permanent impairment of renal function and some patients required long–term dialysis. While some cases have occurred in patients without identifiable risk factors, patients at increased risk of acute phosphate nephropathy may include those with increased age, hypovolemia, increased bowel transit time (such as bowel obstruction), active colitis, or baseline kidney disease, and those using medicines that affect renal perfusion or function (such as diuretics, angiotensin converting enzyme [ACE] inhibitors, angiotensin receptor blockers [ARBs], and possibly nonsteroidal anti–inflammatory drugs [NSAIDs]).

It is important to use the dose and dosing regimen as recommended (PM/AM split dose).

OSMOPREP® (sodium phosphate monobasic monohydrate, USP, and sodium phosphate dibasic anhydrous, USP) Tablets are contraindicated in patients with a biopsy-proven acute phosphate nephropathy, gastrointestinal (GI) obstruction, gastric bypass or stapling surgery, bowel perforation, toxic colitis, toxic megacolon, and known allergy or hypersensitivity to sodium phosphate salts or any component of OSMOPREP.

Renal impairment may occur with OSMOPREP. Assess renal function before treatment and during therapy. Use OSMOPREP with caution in patients with impaired renal function (creatinine clearance less than 30mL/minute), patients with a history of acute phosphate nephropathy, known or suspected electrolyte disturbances (such as dehydration), or people taking concomitant medications that may affect electrolyte levels (such as diuretics). Patients with electrolyte abnormalities (such as hypernatremia, hyperphosphatemia, hypokalemia, or hypocalcemia) should have their electrolytes corrected before treatment with OSMOPREP Tablets.

Seizures due to electrolyte abnormalities can occur. OSMOPREP should be used with caution in patients with a history of seizures or at higher risk of seizure [e.g. patients using concomitant medications that lower the seizure threshold (such as tricyclic antidepressants), patients withdrawing from alcohol or benzodiazepines, or patients with known or suspected hyponatremia].

Use caution in patients with higher risk of arrhythmias (e.g., patients with a history of cardiomyopathy, prolonged QT, uncontrolled arrhythmias, or recent myocardial infarction).

Advise patients to hydrate adequately before, during, and after the use of OSMOPREP.

Use OSMOPREP with caution in patients with history of Inflammatory Bowel Disease. In patients with suspected GI obstruction or perforation, rule out the diagnosis before administration of OSMOPREP.

Animal reproduction studies have not been performed. OSMOPREP should only be given to a pregnant woman if clearly needed.

In clinical trials, the most commonly reported adverse reactions (reporting frequency >3%) were abdominal bloating, abdominal pain, nausea, and vomiting.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch/ or call 1-800-FDA-1088.

For product information, adverse event reports, and product complaint reports, please contact:

Salix Product Information Call Center
Phone: 1-800-508-0024
Fax: 1-510-595-8183
Email: salix@medcomsol.com

Please see complete Prescribing Information for OSMOPREP, including BOXED WARNING.

The information contained on this page is intended for US patients, healthcare professionals, and pharmacists only.


SWB 12/03