Constipation Medications (Laxatives)

Pharmacy and Therapeutics

First Line Drugs: 1) Bulk-forming agents, 2) Tension reduces (stool softeners), 3) Osmotic laxatives.
Route: Oral
Second Line Drugs: 1) Stimulants, 2) Suppositories / Enemas.
Route: Oral or Rectal
Other Drugs: Lubiprostone, Linaclotide, Methylnaltrexone, Naloxegol

Treatment Algorithm for constipation from the AAFP, 2015

The following table of treatment options can be seen presented with pictures in my powerpoint on treating constipation here.

All doses shown here are po unless otherwise noted.
Mnemonic for constipation medications: OBSTipation, see here.

Medication

Usual adult dose / MOA

Onset of action

Side effects
/Caution

Osmotic Agents

Polyethylene glycol 3350 (MiraLax) 17 g/day PO dissolved in 4 to 8 oz of beverage
Lactulose 15 to 60 mL PO QHS
Sorbitol: 15 to 60 mL PO QHS
Magnesium salts (milk of magnesia) 15 to 30 ml PO once daily; avoid in renal insufficiency
Polyethylene glycol 3350 (macrogol)
Miralax
(PEG is superior to lactulose/sorbitol)
Comes as a powder: 17 g per capful or 17 g per packet.		 Adults: 17 g PO QD.
Pediatrics: 0.8 g/kg/day PO QD prn. Max: 17 g/day
Dissolve it in 4-8 oz (i.e. 120-240 ml) of liquid (water, juice, soda or coffee, etc.)		 1 to 4 days Nausea, bloating, cramping
Lactulose
Dispensed as a solution: 10 g per 15 ml		 10 to 20 grams (15 to 30 mL) every other day. May increase up to 2 times per day. 1 to 2 days Abdominal bloating, flatulence
Sorbitol (as effective as lactulose) 30 grams (120 mL of 25 percent solution) 1 time per day 1 to 2 days Abdominal bloating, flatulence
Glycerin (glycerol)
-Suppository		 One suppository (2 or 3 grams) per rectum for 15 minutes 1 time per day 15 to 60 minutes Rectal irritation
Magnesium sulfate One to two teaspoonsful (≅5 to 10 grams) dissolved in 240 mL (8 ounces) water 1 time per day 0.5 to 3 h Watery stools and urgency. Avoid in renal insufficiency (magnesium toxicity).
Magnesium citrate
Comes as a
Solution: 1.745 g per 30 ml.		 Constipation, acute
150-300 ml/day PO divided qd-bid. Max: 300 ml/day.
Bowel Prep
150-300ml PO x1		 0.5 to 3 h
Magnesium Hydroxide (Milk of Magnesia)
Comes as a Suspension: 400 mg per 5ml, 1200 mg per 5 ml		 2400-4800mg po QD prn.
Alt, you can divide it into bid-qid prn. Don’t use in renal failure pts.

Bulk-forming laxatives

Psyllium (e.g. Metamucil): 1 tbsp in 8-oz liquid PO daily up to TID
Methylcellulose (Citrucel): 1 tbsp in 8-oz liquid PO daily up to TID
Polycarbophil (Mitrolan, FiberCon): 2 caplets with 8-oz liquid PO up to QID
Patient must drink an adequate amount of fluids for bulking agents to work. If not they might actually worsen constipation.
Psyllium
(eg. Metamucil)		 Up to 1 tablespoon (≅3.5 grams fiber) 3 times per day 12 to 72 h Impaction above strictures, fluid overload, gas and bloating
Methylcellulose
(e.g. Citrucel)		 Up to 1 tablespoon (≅2 grams fiber) or 4 caplets (500 mg fiber per caplet) 3 times per day 12 to 72 h
Polycarbophil
(e.g. FiberCon)		 2 to 4 tabs (500 mg fiber per tab) per day 1  to 2 days
Wheat dextrin
(e.g. Benefiber)		 1 to 3 caplets (1 gram fiber per caplet) or 2 teaspoonsful (1.5 gram fiber per teaspoon) up to 3 times per daily 1 to 2 days

Stimulant Laxatives

Don’t use stimulants for more than 1 week!
Bisacodyl (Dulcolax) 5mg, take 1 to 3 tablets PO daily
Senna/docusate (Senokot-S): 1 to 2 tablets or 15 to 30 mL PO at bedtime
Bisacodyl
(Dulcolax)
Comes as 5mg tabs.
(enteric coated tabs)		 Bisacodyl 5-15mg PO QD.
Max: 30mg/day.
(Do not cut/crush/chew tabs. Avoid use within 1h of antacids or milk; do not use >1wk)		 6 to 10 h Gastric irritation
10 mg suppository per rectum 1 time per day 15 to 60 minutes Rectal irritation
Senna (sennosides) 2 to 4 tabs (8.6 mg Sennosides per tab) or 1 to 2 tabs (15 mg Sennosides per tab) as a single daily dose or divided twice daily 6 to 12 h Melanosis Coli
Combinations:

Docusate sodium / Senna

Tab: 50 mg / 8.6 mg

 Sig: Take 1-2 tabs PO QD-BID 6-12 h Melanosis Coli

Tension-Lowering Agents (I.e. Surfactants or softeners)

Rx: Docusate sodium (Colace): 100 mg PO BID
Docusate sodium
(Colace)		 100 mg PO QD – BID 1 to 3 days Well tolerated. Use lower dose if administered with another laxative. Contact dermatitis reported.
Docusate calcium
(Surfak)		 240 mg PO QD 1 to 3 days

Peripherally Acting mu-Opioid Antagonists.

“Peripherally acting mu-opioid antagonists are expensive and should be used only when other options are ineffective.”
Methylnaltrexone, alvimopan, and Naloxegol decrease the GI effects of opioids without reducing centrally mediated analgesia. Naloxone is also effective for constipation but can decrease analgesia.
 Methylnaltrexone (Relistor)
Given orally (tablet) or SC (prefilled syringe)		 Opioid-induced constipation with chronic non-cancer pain: Oral: 450 mg once daily, OR
SubQ: 12 mg once daily
NB:  D/C all laxatives before initiation; if the response is not optimal after 3 days, laxative therapy may be reinitiated.
Opioid-induced constipation with advanced illness (Palliative care patient): Give SubQ. Use weight-based dosing.		 Do not be used in patients with intestinal obstruction. Use with caution in patients with intestinal cancer.
Naloxegol (Movantik)
Given as oral tablets.		 Opioid-induced constipation (for patients with chronic non-cancer pain): 25 mg PO/NG qam. Give 1-2 hrs before or after a meal.
May give half a tablet (12.5 mg) if the patient doesn’t tolerate it.
Alvimopan (Entereg)
Comes as 12 mg capsule.		 Postop ileus: 12 mg po BID for up to 7 days.

“Approved for short-term treatment of postoperative ileus.
is available only through a restricted prescribing program because of increased risk of myocardial infarction.”
Naloxone  Rarely used to tx opioid-induced constipation alone because of unwanted side effect of analgesia reversal.

Lubiprostone and Linaclotide

Lubiprostone MOA: “Activates CIC-2 chloride channels, increasing intestinal fluid secretion and motility, reducing intestinal permeability, and stimulating recovery of mucosal barrier function.” Epocrates
Linaclotide MOA: “Activates guanylate cyclase-C, stimulating cGMP production and increasing intestinal fluid secretion and motility” Epocrates
Lubiprostone (Amitiza)
For: 1) IBS-C, 2) Chronic idiopathic constipation, 3) Opioid-induced constipation
Comes as capsules		 24 microgram capsule PO BID
**FDA approved for long-term treatment of chronic constipation in adults.		 1 to 2 days Nausea, diarrhea
Linaclotide (Linzess)
For: IBS-C and Chronic idiopathic constipation.
Comes as capsules containing 72 mcg, 145 mcg, or 290 mcg		 145 micrograms PO QD
Ie. it works by increasing intestinal fluid secretion and motility.
**FDA approved for chronic constipation and irritable bowel syndrome.		 12 to 24 h Diarrhea, bloating

IBS-C = IBS constipation predominant
MOA = Mechanism of action
Phosphate-containing laxatives are not recommended. Mineral oil (enema and oral liquid) laxatives are not generally recommended except as enema following dis-impaction

A Powerful Laxative Concoction

MOM + Warm prune juice po. This works miracles, many experienced nurses will tell you this!

XR Barium Enema

When constipation in a hospitalized patient is really bad, consider doing a XR barium enema. Interventional Radiology does it and gets pictures. It often gets patients to have a bowell movement.

Enemas and Suppositories

SMOG enema= SMOG (Saline, Mineral Oil, Glycerin) enema. Mix 50cc of each. Give this after laxatives, enema, etc fail.
Milk and Molasses enema (Dr. Streletz loves it)
Fleet Enema, Mineral oil enema can also be used separately.
Mineral oil enema
Osmotic: sodium phosphate
Lubricant: Glycerin enema/rectal
Stimulatory: Bisacodyl enema
Enemas: Saline (Fleet enema)

** Fleet is the name of the company. Fleetlabs.com

Further Reading / Reference
Am Fam Physician. 2015 Sep 15;92(6):500-504.

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