Thursday, July 19, 2007

Vitamins, Medications, and Malabsorption After WLS

Everyone out there in post WLS land know the drill when it comes to vitamins. Practically every center has the same guidelines, a multivitamin, B12, calcium, and iron. But is that enough to waylay all the nutritional deficits caused by WLS, especially RNY. RNY happens to be the most prevalent type of WLS done at this time. It's the type I have.

I am going to be doing some in depth posts in the coming weeks concerning this very thing. I did post some links in the previous posts, but I feel the need to go more in depth.

The first thing that needs to be discussed above anything else, just what malabsorption is and how we need to look at taking anything--especially vitamins and medications--in a different light.

First let's review the types of WLS available. This is taken from Medscape. You have to have an account to be able to view the articles, so I'll just hit the highlights here. The full article is this: Medication and Nutrient Administration Considerations After Bariatric Surgery

Types of Bariatric Surgery

Bariatric surgery is categorized by surgical technique (i.e., restrictive procedure or a combination of restrictive and malabsorptive procedures). During restrictive procedures, a small pouch is created at the top of the stomach. Food passes through a small hole (≈1 cm) created at the bottom of the pouch and then through the remainder of the gastrointestinal tract. The smaller pouch limits the quantity of food that patients can consume, and the small opening slows emptying to create a prolonged sensation of satiety. Restrictive procedures include verticalbanded gastroplasty and adjustable gastric banding. With vertical-banded gastroplasty, a vertical section of the upper stomach is stapled to form a pouch. A small stoma is formed at the bottom of the pouch using a polypropylene band (Figure 1A). Adjustable gastric banding involves placement of a silicone ring around the upper portion of the stomach. The diameter is adjusted by adding saline to partition off the stomach and create a small opening at the bottom (Figure 1B). Adjustable gastric banding has been widely performed in Australia and recently performed in the United States. Both procedures produce less dramatic weight loss than do combination procedures and are performed less commonly than combination restrictive and malabsorptive procedures in the United States.

Figure 1.

A. Vertical-banded gastroplasty. A vertical section of the stomach is stapled to form a pouch. A small stoma is formed at the bottom of the pouch using a polypropylene band. B. Adjustable gastric banding. This involves placement of a silicone ring around the upper portion of the stomach. The diameter is adjusted by adding saline to partition off the stomach and create a small opening at the bottom. C. Roux-en-Y gastric bypass. The small intestine is reconnected to bypass the duodenum, the jejunum, and all but the last 50-100 cm of the ileum.

The combination restrictive–malabsorptive procedures most commonly performed include biliopancreatic diversion and the Roux-en-Y gastric bypass. Biliopancreatic diversion involves removal of up to 75% of the stomach. The small intestine, which produces digestive enzymes essential for the breakdown and absorption of fats and proteins, is reconnected to bypass the duodenum, the jejunum, and all but the last 50–100 cm of the ileum. By bypassing a majority of the small intestine and limiting the amount of food exposed to digestive enzyme, very little consumed fat and protein are absorbed. While this procedure is very effective, the drastic reduction in functional intestine length places patients at high risk for nutritional deficiencies that can be difficult to replace and is generally reserved for patients with a BMI of ≥50.

Roux-en-Y gastric bypass is the most frequently performed bariatric surgery in the United States (Figure 1C). The restrictive portion of the procedure entails separating, by stapling or transection, a 30–60-mL pouch in the stomach to restrict food intake. The small pouch produces much less gastric acid and has a higher pH than the stomach as a whole. The small intestine is cut 45 cm from the base of the stomach, and the lower intestine (termed the Roux limb) is connected to the pouch at the top of the stomach. The connection to the intestine is ≈1 cm in diameter to slow emptying from the stomach and maintain a feeling of fullness for an extended period of time. The portion of the small intestine connected to the lower portion of the stomach is also connected to the Roux limb to allow some acid and digestive enzymes to reach passing food and facilitate digestion. By bypassing the lower stomach and a majority of the small intestine, malabsorption occurs. Patients who have undergone this surgery are also at risk for nutrient deficiencies. However, unlike with biliopancreatic diversion, supplementation can easily be achieved in these patients. Several factors, such as pH and absorption sites, should be considered when providing these patients with appropriate supplementation

Because the RNY is the most common procedure done at this time---hey I have it---that is what I will address in these posts.

Drug Absorption after Bariatric Surgery

The solubility of a drug, surface area for absorption, and blood flow to the gastrointestinal tract influence oral absorption and bioavailability. Drug solubility and surface area for absorption are affected by gastric bypass procedures. Drugs in aqueous solution are more rapidly absorbed than those in oily solutions, suspensions, or solid form. When medications are given as tablets, the times to disintegration and dissolution of the tablet affect absorption. In early drug trials, these factors are accounted and adjusted for to ensure adequate absorption in patients with unaltered gastrointestinal tracts. However, reductions in the amount of functioning gastrointestinal tract after gastric bypass surgery lead to decreased time to drug absorption and reduced drug bioavailability.

The solubility of drugs is affected by pH. Drugs that are more soluble at an acidic pH are absorbed in the stomach, and those soluble in al kaline environments are absorbed in the small intestine. In addition, some drugs depend on the enzymes in the small intestine to aid in their absorption. In patients who have had gastric bypass surgery, the small pouch located at the top of the stomach produces much less hydrochloric acid than the stomach previously did, possibly decreasing the absorption of medications dependent on acidic environments for solubility or absorption.

By bypassing major portions of the small intestine, Roux-en-Y bypass procedures drastically reduce the surface area for absorption. Villi and microvilli give the small intestine a much greater surface area than the large intestine. Thus, bypassing of the duodenum and jejenum represents a large loss of surface area for absorption. These changes may warrant manipulation in drug route or dose to ensure adequate delivery. Drugs with long absorptive phases that remain in the intestine for extended periods are likely to exhibit decreased bioavailability in patients who have undergone this procedure. Therefore, products with prolonged dissolution times, such as extended-release formulations, should be avoided in this population.

Let's break this down shall we. For medications and vitamins to be absorbed the right way many factors come in to play. Is it a liquid, a pill, a capsule. If it is a liquid, is it in a water based formula or does it have a oily based formula. Does the medication or vitamin need to have acid to break it down or an alkaline base. Is it possibly coated---as in extended release or long acting meds (pay attention to this real close---all my fellow Bipolars and those taking meds for depression). All of this is important for our over all long term health once you have WLS. The majority of the problems---LONG TERM---deal with the whole malabsorption issues.

Considerations for Nutrient Replacement

Nutrient deficiencies in patients who have had restrictive procedures have been reported; the exact prevalence is unknown. Because restrictive procedures retain the use of the entire gastrointestinal tract, nutrient deficiencies are less common than in patients who have had gastric bypass procedures. After gastric bypass procedures, patients are prone to deficiencies of the fat-soluble vitamins (A, D, E, and K) and calcium. In addition, these patients have an increased risk of developing anemia secondary to potentially inadequate amounts of iron, vitamin B12, and folate. Because of these deficits, all patients should receive a daily multivitamin and calcium supplementation indefinitely. In patients with anemia, additional supplementation with iron, vitamin B12, and folate may be necessary. The specifics of these deficiencies have been discussed elsewhere.

The partitioning of the stomach during bariatric surgery results in a dramatic decrease in the production of hydrochloric acid, affecting the absorption of calcium and iron. However, absorption can be increased by using different salt forms or manipulating gastric pH. Calcium carbonate depends on acid for its absorption; calcium citrate does not. One study comparing the bioavailability of both products in achlorhydric patients found the bioavailability of calcium carbonate and calcium citrate to be 4% and 45%, respectively. While calcium citrate is more expensive than calcium carbonate, it is logical to specifically recommend calcium supplementation with the citrate salt in this patient population. Decreased calcium absorption can increase the risk of osteoporosis. While specific guidelines to monitor bone density do not exist for these patients, early bone densiometry testing would be prudent.

The duodenum is the primary site for absorption of iron and is bypassed in the Roux-en-Y procedure, creating the potential for nutrient deficiencies. To be absorbed, iron must be in the ferrous state (Fe2+). However, most consumed iron is in the ferric form (Fe3+) and reduced to the ferrous state in the acidic environment of the stomach. The ferrous form is then absorbed in the duodenum. In patients who have had gastric bypass surgery, iron salts can be combined with ascorbic acid (vitamin C) to acidify the stomach environment and facilitate absorption. There are commercially available products that combine these two nutrients.

Vitamin B12 absorption is dependent on the presence of intrinsic factor, which is produced in the parietal cells of the stomach. In addition, hydrochloric acid is necessary to cleave vitamin B12 from protein in the stomach. These variations can lead to deficiencies in patients after gastric bypass surgery. Monthly B12 injections are effective in this population; however, appropriate supplementation can also be achieved by using the oral formulation (1000 µg daily). This helps these patients avoid the inconvenience of frequent health care visits and the pain associated with injections.

This talks about the regular arsenal of vitamins that are important and most bariatric centers recommend. As stated in the beginning of the posts--I plan to go into further detail in coming posts. Something I need to stress here--iron should never be taken with your calcium supplements. Period. No ifs ands or buts about it. They fight for absorption at the same sites in the intestine so neither gets absorbed properly.

Medication Considerations

While very few specific recommendations on optimizing medication regimens exist for patients who have undergone bariatric surgery, some general guidelines can be formulated. The reduced size of the stomach after surgery can place patients at risk for adverse events associated with some medications. One case report described ulceration in a patient after gastric bypass and the use of a nonsteroidal antiinflammatory drug. Most bariatric surgery centers recommend that patients avoid the use of these agents indefinitely to avoid this potentially fatal complication. This complication theoretically extends to the salicylates. Given the lack of primary literature on this topic, the risks and benefits of daily aspirin therapy should be considered on an individual basis. Other options for oral pain medication include acetaminophen, opioids, and tramadol. The oral bisphosphonates (drugs for osteoporosis) are another class of medications that could present problems due to a reduced pouch size, which may increase the risk of gastrointestinal ulceration. Since these patients can be at risk for osteoporosis because of decreased calcium absorption, other treatment options (e.g., calcitonin salmon nasal spray, synthetic parathyroid hormone [teriparatide], raloxifene [for women]) should be considered.

Reductions in drug absorption are more frequently encountered in patients who have had combination restrictive–malabsorptive procedures. Decreased intestinal length and surface area lead to the reduced absorption of extended-release drug preparations because these formulations are absorbed over 2–12 hours. The reduction in functional intestine length makes it likely that extended-release preparations have passed through the gastrointestinal tract before absorption is complete. These same principles can also apply to delayed-release and enteric- or film-coated product formulations. To overcome this problem, the immediate-release dosage forms should be substituted, which could require increased frequency of administration.

Other than extended-release preparations, changes in a patient’s medication regimen are generally unnecessary unless patients have difficulties with decreased efficacy or increased adverse gastrointestinal effects. Consideration of the site of absorption for specific medications can be helpful in determining whether reduced absorption is likely to occur . Drugs that are rapidly and primarily absorbed in the stomach or duodenum are likely to exhibit decreased absorption in patients who have had combination restrictive–malabsorptive procedures. However, it is possible that compensatory absorption by other sites could mean that drugs are still adequately absorbed. Pharmacokinetic studies do not examine this particular effect, and it is generally unknown whether it will occur.

Because reduced drug absorption may result in decreased efficacy rather than toxicity, increased patient monitoring for therapeutic effects can help detect potential absorption problems. If appropriate doses appear to have little or no effect, the possibility of reduced drug absorption should be considered. A change to a liquid medication formulation could increase absorption by eliminating the need for drug dissolution. Other administration approaches, including subcutaneous, intravenous, rectal, vaginal, intranasal, and transdermal routes, should also be considered. However, it is important to consider the effect of obesity on drug absorption from subcutaneous or transdermal routes of administration. Increased monitoring is not effective in the management of potential reduced absorption of oral contraceptives. Obesity’s link to infertility and the weight loss that occurs postsurgery could result in unwanted or unplanned pregnancy. Therefore, nonhormonal, barrier contraception should be recommended for these patients.

The thing I really want to stress here is the extended release, enteric coated, pills. This is very important to grasp this. I personally have had to deal with this issue myself---so listen up. I did a previous post on the prevalence of mental illness in those undergoing WLS---Mental Health and WLS---In this post it was stated the following:

Overall, 66.3% of subjects had a lifetime history of at least one axis I disorder and 37.8% were currently diagnosed with such a disorder. The most common lifetime axis I disorder was major depressive disorder, seen in 42% of subjects. Binge eating disorder was the most common current disorder and had a prevalence of 16.0%.

A lifetime history of an axis II disorder was noted in 28.5% of subjects, the most common being avoidant personality disorder, which was seen in 17.0%.
So taking this info into account---the route of medication truly comes into play for post WLS. Simply because the majority of psych meds are geared to be extended release. A good example is Wellbutrin. I see many post WLSers on this med for depression. The med usually prescribed is Wellbutrin XL or Wellbutrin SR. But it is also available in a standard pill form. That just means you have to take it throughout the day instead of one pill in the morning. But don't you want to make sure you are getting the proper dosage to begin with. Another example that applies to me personally is Depakote (Valproic Acid). When my pdoc first prescribed it he gave me Depakote ER, which is a slow release med. There are many forms of Valproic acid:

Depakote (divalproex sodium) - Valproic Acid
Brand and Generic Names

* Depakene®(Valproic acid) – Immediate release

– Syrup: 250 mg/5mL (there is 250 mg in one teaspoonful)

– Capsules: 250 mg

* Depakote®/Depakote® ER (both Divalproex sodium) – both are enteric-coated and slow release; Depakote® ER releases more slowly than Depakote®.

– Tablets: 125 mg, 250 mg, 500 mg

– Sprinkle capsules: 125 mg

– Slow-release tablets: 250 mg, 500 mg

* Depacon®(Valproate sodium) – Intravenous (IV) formulation

– 100 mg/mL

I had considerable trouble getting my levels within therapeutic range. So I did some research. Now I take it in the liquid form. Was my pdoc aware of the problems with taking medications after WLS? Apparently not. Also another med given for Bipolar disorder is Lamictal(Lamotrigine). It is likely absorbed in the stomach and proximal small intestine due to rapid and complete absorption. So you need to monitor for possible decreased efficacy. Another med I take is Seroquel(quetiapine fumarate).The exact site of absorption is unknown but it is speculated to be absorbed in the stomach or duodenum due to rapid absorption. So you have to monitor it also for decreased efficacy.

As more and more people undergo WLS, it is vital they have all the info they can get there hands on. Living life after WLS is no easy task. Post op instructions vary from surgeon to surgeon. But as health consumers we can NOT afford to just be a bunch of sheep and blindly follow doctors orders.

WHOA---wait a minute there BG---are you saying we don't need to listen to our surgeons???

No that is NOT what I am saying. Your surgeon has experience in this field---first and foremost you need to follow post op recommendations. But they do not give you the full story on long term outcomes. You MUST become proactive in your own health care. Listen to your body. Also do your own research. There are alot of great resources to be found on the net. My favorite being LivingAfterWLS.

You had yourself "gut whacked", to borrow, my good friend and fellow WLSer, Kaye Bailey's term, for a reason. You wanted a healthier more active life. Shouldn't you care enough about yourself to do all you can within your own power to remain that way????


Anonymous said...

I'm very impressed with the info you have on malabsorption issues. I've taken the standard supplements, but have had problems with keeping my iron, calcium, and thyroid hormones in balance since my surgery almost 4 years ago. I still dump a lot and have a lot of classic malabsorption issues like diarhea, stomach crmaping, and a tendency toward anorexia no matter how much I eat (and to think that's something I used to wish for!). I also now have very thin skin on my arms. All I have to do is scratch an itch and I either get a subdural hematoma that looks like an HIV patient's Karposi Sarcoma or the skin simply breaks and scabs. I'm wondering if that has to do with malabsorption of the A or D vitamins now that I read your blog. From what I'm reading, treatment of "dermatoporosis" - what I think I've got - involves using topical retinoids which are derivatives of vitamin A. So it might be logical I should be supplementing more internally as well.

There seem to be so many long term hitches to the Rue N Y that I sometimes wish I'd stuck to my guns and gotten the lap band even though the insurance didn't cover it. Many would envy me now, as I look really great, but I just hope some day I can achieve a better nutritional balance and maintain it.

Thanks again for the primer. It's been very helpful. - Steph