Medication absorption after RNY

[Guest guest]

Hello.

Does anyone know of any research on medication (antidepressant)

absorption and monitoring blood levels for medication absorption after

(distal) RNY? We have a patient who is required by his job to be on

an antidepressant. They do routine blood work to ensure he is

compliant. There are no traces of the medication in his blood and he

insists he is compliant with taking the medication. We are currently

looking for any research on this topic. Any help would be

appreciated. Thank you.

[Guest guest]

See below. (BTW, how can an employer legally require that ANY med be

taken?)

Ask the Experts about Pharmacotherapy

From Medscape Pharmacists

How Does Bariatric Surgery Affect the Absorption of Medications?

QUESTION

I have a patient who underwent gastric bypass surgery recently. I

know that the absorption of medications could be affected by many

factors pertaining to the gastrointestinal system. How does

bariatric surgery affect the absorption of medications?

RESPONSE from Brigette , MS, PharmD,BCNP

Director, Clinical Pharmacy Services, MSC-Medical Services Company,

ville, Florida

The number of bariatric surgical procedures performed in the United

States has risen dramatically, from an estimated 16,000 procedures

in the early 1990s to about 103,000 in 2003.[1] The surgery may

involve a restrictive procedure (ie, vertical-banded gastroplasty or

adjustable gastric banding), or a combination of restrictive and

malabsorptive procedures (ie, biliopancreatic diversion or Roux-en-Y

gastric bypass). Roux-en-Y gastric bypass is the most frequently

performed variety in the United States, and it involves forming a

small stomach pouch to restrict food intake and then reconnecting

the small intestine to the pouch.

Bypassing a large portion of the stomach and small intestine puts

these patients at risk for malabsorption, and it also changes the

absorption of some medications. Patients are prone to deficiencies

in the fat-soluble vitamins (A, D, E, and K) and in calcium.[2,3]

Thus, appropriate supplementation with iron, vitamin B12, calcium,

and folate is an important consideration.[2,3] In some cases,

parenteral iron infusion may be necessary to avoid anemia,

particularly in menstruating women.[3]

Due to changes in the acidic environment and the reduced surface

area for drug absorption, changes in drug delivery route or dose may

be necessary to assure adequate drug concentrations. Avoiding

extended-release formulations is recommended, due to their long

absorptive phase in the intestine.[2,4]

Immediate-release formulations with a more frequent dosing schedule

may be required. It may be useful to use a liquid formulation to

eliminate the drug absorption phase where possible.[2] Other routes,

such as intramuscular, transdermal, subcutaneous, and inhalation,

may be considered. However, it is also important to keep in mind the

impact obesity may have on these routes of administration.[2]

The salt form of medications may also require consideration.[2,4] For

example, calcium citrate does not require stomach acid for bsorption

and would be a more reasonable choice than calcium carbonate, which

requires a higher acid concentration.[2,4]

Nonsteroidal anti-inflammatory drugs (NSAIDs) and oral isphosphonates

should be avoided in this population, since these patients are at

increased risk for ulceration due to the reduced stomach size.[2]

Consider using alternatives for pain relief, such as acetaminophen,

tramadol, and/or opiates. Likewise, alternatives for osteoporosis

prevention can be used.[2]

For gastric bypass patients, it is thus appropriate to regard these

factors: route of drug administration, salt formation, monitoring of

medication blood levels to assure therapeutic concentrations, and

appropriate nutrient and vitamin supplementation. As indicated, the

impact of obesity and changes in lean body mass may also be

important considerations when choosing drug form and dose.[2,5]

Posted 12/18/2006

References

1. Buchwald H, Avidor Y, Braunwald E, et al. Bariatric surgery: a

systematic review and meta-analysis. JAMA. 2004:292:1724-1737.

Abstract

2. AD, KM. Medication and nutrient administration

considerations after bariatric surgery. Am J Health-Syst Pharm.

2006;63:1852-1857.

3. Virji A, Murr MM. Caring for patients after bariatric surgery.

Am Fam Physician. 2006;73:1403-1408. Abstract

4. Fussy SA. The skinny on gastric bypass: what pharmacists need

to know. US Pharm. 2005;2:HS-3-HS-12.

5. Malone M. Altered drug disposition in obesity and after

bariatric surgery. Nutr Clin Pract. 2003;18:131-135. Abstract

From http://www.medscape.com/viewarticle/548664

Ava

>

> Hello.

> Does anyone know of any research on medication (antidepressant)

> absorption and monitoring blood levels for medication absorption

after

> (distal) RNY? We have a patient who is required by his job to be

on

> an antidepressant. They do routine blood work to ensure he is

> compliant. There are no traces of the medication in his blood and

he

> insists he is compliant with taking the medication. We are

currently

> looking for any research on this topic. Any help would be

> appreciated. Thank you.

>

[Guest guest]

Some or all of antidepressant medications are bound to serum proteins

(i.e. albumin). Is his protein intake adequate?

>

> Hello.

> Does anyone know of any research on medication (antidepressant)

> absorption and monitoring blood levels for medication absorption

after

> (distal) RNY? We have a patient who is required by his job to be on

> an antidepressant. They do routine blood work to ensure he is

> compliant. There are no traces of the medication in his blood and he

> insists he is compliant with taking the medication. We are currently

> looking for any research on this topic. Any help would be

> appreciated. Thank you.

>