This chapter will review the pharmacotherapy for management of gastrointestinal (GI) fistulas, postoperative ileus, nausea, and vomiting and upper GI bleeding according to expert opinion.
GI fistulas
Definition
An abnormal connection between the GI track and the skin, another internal organ, or an internal cavity.
Causes
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Postoperative fistulas (most common; 80%)
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Spontaneous fistulas (Crohn disease and inflammatory bowel disease are the leading cause)
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Trauma-induced fistulas
Management
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Fluid resuscitation and electrolyte management (see Chapter 21 )
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Drainage
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Nutrition (enteral vs. parenteral)
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Octreotide
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Mimics natural somatostatin found in the GI by inhibiting hormone secretion, exocrine secretory response, GI motor activity, and nutrient absorption and stimulation of water and electrolyte absorption.
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Dose: 100 mcg subcutaneously three times daily
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Discontinue if no response within 48 h
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Postoperative ileus (POI)
Definition
A transient GI dysmotility following a surgery.
Causes
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Increased sympathetic stimulation postoperatively
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Damage to the vagal nerve during abdominal surgery
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Inflammation of the GI tract after surgery
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Drugs: anesthetics, opioids, anticholinergics
Pharmacologic management ( table 8.1 )
| DRUG | STANDARD DOSING | COMMENTS |
|---|---|---|
| Opioid-Sparing Analgesic Agents: NSAIDs | ||
| Ketorolac (Toradol) 15 mg, 30 mg injection | 15–30 mg IV q6h PRN Max: 5 days | Opioid sparing via analgesic and anti-inflammatory effects. Need to ensure adequate hydration prior to NSAID use. CrCl <30: avoid use |
| Ibuprofen (Caldolor) 800 mg injection | 400–800 mg IV q6h PRN | |
| Diclofenac (Dyloject) 37.5 mg injection | 37.5 mg IV q6h PRN | “ |
| Laxatives | ||
| Bisacodyl (Dulcolax) 10 mg suppository | 10 mg rectally daily | Stimulant laxative |
| Peripherally Acting Mu-Opioid Receptor Antagonists | ||
| Alvimopan (Entereg) 12 mg capsule | 12 mg PO 0.5–5 h prior to surgery, followed by 12 mg BID beginning the day after surgery up to 7 days | FDA approved for POI 200-fold selectivity for the peripheral opioid receptors Poor GI/systemic absorption REMS drug |
| Methylnaltrexone (Relistor) 8 mg, 12 mg injection | 0.15 mg/kg SubQ daily or every other day | FDA approved for chronic opioid-induced constipation, not POI. Does not affect opioid analgesic effects. Does not cross the blood-brain barrier. Discontinue all laxatives prior to use; restart laxatives PRN if suboptimal response to methylnaltrexone or naloxegol after 3 days |
| Naloxegol (Movantik) 12.5 mg, 25 mg tablet | 25 mg PO daily 12.5 mg if 25 mg not tolerated | |
| Prokinetic Agents | ||
| Erythromycin (Erythrocin) 250 mg, 500 mg tablet 500 mg injection 200–400 mg/5 mL oral suspension | IV: 3 mg/kg over 45 min q8h PO: 250–500 mg (base) TID AC | Macrolide antibiotic with prokinetic activity Off-label use; inconsistent data Erythromycin ethylsuccinate 400 mg = erythromycin base or stearate 250 mg |
| Metoclopramide (Reglan) 10 mg injection 5 mg, 10 mg tablet 1 mg/mL oral solution | PO, IM, IV, SubQ: 5–10 mg BID–TID AC PO route preferred | Prokinetic and antiemetic activity Off-label use; inconsistent data Decrease dose by 50% in CrCl <40 (IV) and CrCl ≤60 (PO) |
| Prucalopride (Motegrity) 1 mg, 2 mg tablet | 2 mg PO daily CrCl <30: 1 mg PO daily ESRD on HD: avoid | Serotonin 5-HT4 receptor agonist Off-label use Start before surgery ADR: headache, abdominal pain, nausea, diarrhea |
| Tegaserod (Zelnorm) 2 mg, 6 mg tablet | Females <65 years: 6 mg PO BID AC (dosing for IBSC or CIC) | Serotonin 5-HT4 receptor agonist FDA approved for emergency treatment of IBSC and CIC in women <55 years without alternative therapy option |
Postoperative nausea and vomiting (PONV)
Definition
Nausea, vomiting, or retching in the immediate 24 postoperative hours.
Risk of PONV ( table 8.2 )
| Risk factors | Female gender Nonsmoker History of motion sickness or previous PONV Expected administration of postoperative opioids |
| No risk factor (low risk) One risk factor (low risk) Two risk factors (medium risk) Three risk factors (medium risk) Four risk factors (high risk) | 10% of PONV 20% of PONV 40% of PONV 60% of PONV 80% of PONV |
Management of PONV
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Treatment algorithm according to risk factors ( Fig. 8.1 )
