Does Welchol (colesevelam) cause side effects?

Welchol (colesevelam) is a lipid-lowering and glucose-lowering agent that lowers cholesterol levels in the blood. It also improves control of blood sugar in type 2 diabetes

Cholesterol made by the liver or from the food we eat can be converted into bile acids by the liver. The bile acids are secreted by the liver into the bile and enter the intestine with the bile. In the intestine the bile acids assist with the digestion of fat.

Some of the bile acids are excreted from the body with the stool, but the majority of bile acids are absorbed from the intestine into the blood, are removed by the liver from the blood, and are re-secreted into the bile. 

Welchol binds bile acids in the intestine and causes more of the bile acids to be excreted in the stool. This reduces the amount of bile acids that returns to the liver and forces the liver to make more bile acids to replace the bile acids lost in the stool.

In order to make more bile acids, the liver converts more cholesterol into bile acids, and this lowers the level of cholesterol in the blood. Welchol is not absorbed into the body. The mechanism whereby Welchol improves blood sugar levels in people with diabetes is unknown.

Common side effects of Welchol include

Serious side effects of Welchol include

Drug interactions of Welchol include cyclosporine, glyburide, levothyroxine sodium, and oral contraceptives containing ethinyl estradiol or norethindrone because Welchol reduces the absorption of these drugs by binding to them in the stomach and preventing their absorption into the body.

  • Welchol also may reduce the activity of phenytoin and warfarin.
  • Drugs that interact with Welchol should be administered four hours before the administration of Welchol and, when possible, drug levels should be monitored. 

Although Welchol has not been studied in pregnant women, it has not been shown to cause birth defects or other problems in animal studies. 

It is unknown if Welchol passes into breast milk, but very little Welchol is absorbed from the intestine and is available for secretion in breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breastfeeding

Welchol may decrease the absorption of certain vitamins that are important during breastfeeding. Mothers who are taking Welchol and who wish to breastfeed should discuss this with their doctor.

What are the important side effects of Welchol (colesevelam)?

Colesevelam usually is well-tolerated. Side effects may include:

Welchol (colesevelam) side effects list for healthcare professionals

The following important adverse reactions are described below and elsewhere in the labeling:

  • Hypertriglyceridemia and Pancreatitis
  • Gastrointestinal Obstruction
  • Vitamin K or Fat-Soluble Vitamin Deficiencies

Clinical Studies Experience

Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in clinical studies of another drug and may not reflect the rates observed in practice.

Primary Hyperlipidemia

In 7 double-blind, placebo-controlled clinical trials, 807 patients with primary hyperlipidemia (age range 18-86 years, 50% women, 90% Caucasians, 7% Blacks, 2% Hispanics, 1% Asians) and elevated LDL-C were treated with Welchol 1.5 g/day to 4.5 g/day from 4 to 24 weeks (total exposure 199 patient-years).

Table 1 : Clinical Studies of Welchol for Primary Hyperlipidemia: Adverse Reactions Reported in ≥ 2% of Patients and More Commonly than in Placebo

Welchol
N=807
Placebo
N=258
Constipation11.0%7.0%
Dyspepsia8.3%3.5%
Nausea4.2%3.9%
Accidental injury3.7%2.7%
Asthenia3.6%1.9%
Pharyngitis3.2%1.9%
Flu syndrome3.2%3.1%
Rhinitis3.2%3.1%
Myalgia2.1%0.4%

Pediatric Patients 10 To 17 Years Of Age

In an 8-week double-blind, placebo-controlled study, boys and post-menarchal girls, 10 to 17 years of age, with HeFH (n=194), were treated with Welchol tablets (1.9-3.8 g, daily) or placebo tablets.

Table 2 : Clinical Study of Welchol for Primary Hyperlipidemia in HeFH Pediatric Patients: Adverse Reactions Reported in ≥2% of Patients and More Commonly than in Placebo

Welchol
N=129
Placebo
N=65
Nasopharyngitis6.2%4.6%
Headache3.9%3.1%
Fatigue3.9%1.5%
Creatine Phosphokinase Increase2.3%0.0%
Rhinitis2.3%0.0%
Vomiting2.3%1.5%

The reported adverse reactions during the additional 18-week open-label treatment period with Welchol 3.8 g per day were similar to those during the double-blind period and included

Type 2 Diabetes Mellitus

  • In 5 add-on combination and 1 monotherapy double-blind, 12-to 26-week, placebo-controlled clinical trials in patients with type 2 diabetes mellitus, 1022 patients were treated with Welchol.
  • The mean exposure duration was 20 weeks (total exposure 393 patient-years).
  • Patients were to receive 3.8 grams of Welchol per day.
  • The mean age of patients was 55.7 years, 52.8 percent of the population was male and 61.9% were Caucasian, 4.8% were Asian, and 15.9% were Black or African American.
  • At baseline the population had a mean HbA1C of 8.2%, and 26% had past medical history suggestive of microvascular complications of diabetes.
  • Table 3 shows adverse reactions associated with the use of Welchol in patients with type 2 diabetes.
  • These adverse reactions were not present at baseline, occurred more commonly on Welchol than on placebo, and occurred in at least 2% of patients treated with Welchol.

Table 3 : Clinical Studies of Welchol for Type 2 Diabetes: Adverse Reactions Reported in ≥2% of Patients and More Commonly than in Placebo

Welchol
N=1022
Placebo
N=1010
Constipation6.5%2.2%
Hypoglycemia3.4%3.1%
Dyspepsia2.8%1.0%
Nausea2.6%1.6%
Hypertension2.6%1.9%
Back Pain2.3%1.3%

  • A total of 5.3% of Welchol-treated patients and 3.6% of placebo-treated patients were discontinued from the diabetes trials due to adverse reactions.
  • This difference was driven mostly by gastrointestinal adverse reactions such as abdominal pain and constipation.
  • One patient in the add-on to sulfonylurea trial discontinued due to body rash and mouth blistering that occurred on the first day of dosing of Welchol, which may represent a hypersensitivity reaction to Welchol.
Hypertriglyceridemia
  • Patients with fasting serum TG levels above 500 mg/dL were excluded from the diabetes clinical trials.
  • In the diabetes trials, 1292 (67.7%) patients had baseline fasting serum TG levels less than 200 mg/dL, 426 (22.3%) had baseline fasting serum TG levels between 200 and less than 300 mg/dL, 175 (9.2%) had baseline fasting serum TG levels between 300 and 500 mg/dL, and 16 (0.8%) had fasting serum TG levels greater than or equal to 500 mg/dL.
  • The median baseline fasting TG concentration for the study population was 160 mg/dL; the median post-treatment fasting TG was 180 mg/dL in the Welchol group and 162 mg/dL in the placebo group.
  • Welchol therapy resulted in a median placebo-corrected increase in serum TG of 9.7% (p=0.03) in the monotherapy study and of 5% (p=0.22), 11% (p<0.001), 18% (p<0.001), and 22% (p<0.001), when added to metformin, pioglitazone, sulfonylureas, and insulin, respectively.
  • In comparison, Welchol resulted in a median increase in serum TG of 5% compared to placebo (p=0.42) in a 24-week monotherapy lipid-lowering trial.
  • Fasting TG concentrations ≥500 mg/dL occurred in 0.9% of Welchol-treated patients compared to 0.7% of placebo-treated patients in the diabetes trials.
  • Among these patients, the TG concentrations with Welchol (median 606 mg/dL; interquartile range 570-794 mg/dL) were similar to that observed with placebo (median 663 mg/dL; interquartile range 542-984 mg/dL).
  • Five (0.6%) patients on Welchol and 3 (0.3%) patients on placebo developed TG elevations >1000 mg/dL.
Cardiovascular Adverse Reactions
  • During the diabetes trials, the incidence of patients with serious adverse reactions involving the cardiovascular system was 2.2% (22/1022) in the Welchol group and 1% (10/1010) in the placebo group.
  • These overall rates included disparate events (e.g., myocardial infarction, aortic stenosis, and bradycardia); therefore, the significance of this imbalance is unknown.

Post-marketing Experience

The following additional adverse reactions have been identified during post-approval use of Welchol. Because these reactions are reported voluntarily from a population of uncertain size, it is generally not possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Adverse Reactions Resulting From Drug Interactions
  • Increased seizure activity or decreased phenytoin levels in patients receiving phenytoin, reduced International Normalized Ratio (INR) in patients receiving warfarin therapy, and elevated thyroid-stimulating hormone (TSH) in patients receiving thyroid hormone replacement therapy
Gastrointestinal
  • Bowel obstruction (in patients with a history of bowel obstruction or resection), dysphagia or esophageal obstruction (occasionally requiring medical intervention), fecal impaction, pancreatitis, abdominal distension, exacerbation of hemorrhoids, and increased transaminases
Laboratory Abnormalities
  • Hypertriglyceridemia

What drugs interact with Welchol (colesevelam)?

Welchol Drug Interactions That Decrease The Exposure Of The Concomitant Medication

Table 4 includes a list of drugs that decrease exposure of the concomitant medication when administered concomitantly with Welchol and instructions for preventing or managing them.

Table 4 : Welchol Drug Interactions that Decrease the Exposure of theConcomitant Medication

Drugs with a Narrow Therapeutic Index
Clinical Impact: Concomitant use with Welchol may decrease the exposure of the narrow therapeutic index drug. In vivo drug interactions studies showed a decrease in exposure of cyclosporine when coadministered with Welchol.
Intervention:Administer the narrow therapeutic index drug at least 4 hours prior to Welchol. Monitor drug levels when appropriate.
Examples:Cyclosporine
Phenytoin
Clinical Impact: There have been postmarketing reports of increased seizure activity or decreased phenytoin levels in patients receiving phenytoin.
Intervention:Administer phenytoin 4 hours prior to Welchol.
Thyroid Hormone Replacement Therapy
Clinical Impact: In vivo drug interactions studies showed a decrease in exposure of levothyroxine when coadministered with Welchol. There have been postmarketing reports of elevated thyroid-stimulating hormone (TSH) in patients receiving thyroid hormone replacement therapy.
Intervention:Administer thyroid hormone replacement therapy 4 hours prior to Welchol.
Warfarin
Clinical Impact: There have been postmarketing reports of reduced INR in patients receiving warfarin therapy.
Intervention:Monitor INR frequently during Welchol initiation then periodically thereafter.
Oral Contraceptives Containing Ethinyl Estradiol and Norethindrone
Clinical Impact: In vivo drug interactions studies showed a decrease in exposure of ethinyl estradiol and norethindrone when coadministered with Welchol.
Intervention:Administer oral contraceptives containing ethinyl estradiol and norethindrone 4 hours prior to Welchol.
Olmesartan Medoxomil
Clinical Impact: In vivo drug interactions studies showed a decrease in olmesartan medoxomil when coadministered with Welchol.
Intervention:Administer olmesartan medoxomil 4 hours prior to Welchol.
Sulfonylureas
Clinical Impact: In vivo drug interactions studies showed a decrease in sulfonylureas when coadministered with Welchol.
Intervention:Administer sulfonylureas 4 hours prior to Welchol.
Examples:Glimepiride, glipizide, and glyburide
Oral Vitamin Supplements
Clinical Impact: Welchol may decrease the absorption of fat-soluble vitamins A, D, E, and K.
Intervention:Patients on oral vitamin supplementation should take their vitamins at least 4 hours prior to Welchol.

Welchol Drug Interactions That Increase The Exposure Of The Concomitant Medication

Table 5 : Welchol Drug Interactions that Increase the Exposure of theConcomitant Medication

Metformin Extended Release (ER)
Clinical Impact: In vivo drug interactions studies showed an increase in metformin extended release (ER) when coadministered with Welchol.
Metformin Extended Release (ER)
Intervention:Monitor patients’ glycemic control.

Treatment & Diagnosis

Medications & Supplements

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Medically Reviewed on 12/31/2020
References
FDA Prescribing Information

Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.