Study of effect of drugs on gastrointestinal motility

Aim: Study of effect of drugs on gastrointestinal motility.

References

1. Malagelada, J. R., & Camilleri, M. (1984). “Gastrointestinal Motility and Pharmacology.” New England Journal of Medicine, 311(22), 1361-1373.
2. De Ponti, F. (2002). “Pharmacology of Prokinetics: Focus on Therapeutic Potential.” Drugs, 62(3), 341-356.
3. Nagakura, Y., & Asano, M. (2006). “Assessment of Gastrointestinal Transit Using the Charcoal Meal Test in Rodents.” Journal of Pharmacological Sciences, 100(3), 233-243.

1. Objective

To evaluate the effect of various drugs on gastrointestinal (GI) motility in experimental animals using standard techniques such as charcoal meal test, BaSO₄ meal test, and intestinal transit measurement.

2. Principle

Gastrointestinal motility refers to the movement of food and secretions through the digestive tract, which is regulated by the enteric nervous system and various neurotransmitters. Drugs such as prokinetics (e.g., metoclopramide), antispasmodics (e.g., atropine), and laxatives (e.g., bisacodyl) can influence GI motility. Their effects can be assessed by measuring the transit of markers like activated charcoal or barium sulfate through the digestive tract.

3. Materials Required

• Animals: Healthy Wistar rats or mice (25-30 g)
• Reagents and Chemicals:
  • Test drugs (prokinetics, antispasmodics, laxatives)
  • Activated charcoal suspension (3% in 0.5% CMC)
  • Barium sulfate (BaSO₄) suspension (10% w/v)
  • Normal saline
  • Atropine sulfate (0.1 mg/kg, i.p.)
  • Metoclopramide (10 mg/kg, i.p.)
  • Bisacodyl (5 mg/kg, p.o.)
• Equipment:
  • Syringes and oral gavage
  • Dissecting instruments
  • Graduated scale for measurement
  • Dissecting microscope
  • Stopwatch

4. Experimental Procedure

4.1. Charcoal Meal Test (Gastrointestinal Transit Test)

1. Animal Grouping:

Control group: Received normal saline (1 mL/kg, p.o.)

Prokinetic group: Received metoclopramide (10 mg/kg, i.p.)

Antispasmodic group: Received atropine (0.1 mg/kg, i.p.)

Laxative group: Received bisacodyl (5 mg/kg, p.o.)

• Procedure:
• Fast animals for 18 hours before the experiment.
• Administer respective drugs 30 minutes before the test.
• Administer 3% activated charcoal suspension (1 mL, p.o.).
• After 30 minutes, sacrifice animals and remove the intestine.
• Measure the distance traveled by the charcoal marker from the pylorus to the ileocecal junction.
• Calculate Gastrointestinal Motility Index (GMI):

4.2. Barium Sulfate (BaSO₄) Meal Test

1. Procedure:
2. Fast animals for 18 hours before the test.
3. Administer test drugs as per grouping.
4. Give 10% BaSO₄ suspension (1 mL, p.o.).
5. At 20-minute intervals, take X-ray imaging or dissect the intestine to observe BaSO₄ transit.
6. Measure the distance moved by BaSO₄ and compare among groups.

5. Observations & Data Analysis

Group	Distance Traveled by Marker (cm)	Total Intestinal Length (cm)	GMI (%)
Control	25	50	50
Prokinetic (Metoclopramide)	40	50	80
Antispasmodic (Atropine)	15	50	30
Laxative (Bisacodyl)	35	50	70

6. Interpretation of Results

• Higher GMI (%) indicates increased GI motility (e.g., prokinetics, laxatives).
• Lower GMI (%) suggests decreased GI motility (e.g., antispasmodics).
• Drugs can be categorized based on their effects on intestinal transit.

7. Precautions

• Maintain fasting conditions for accurate results.
• Ensure correct administration of drugs and markers.
• Use appropriate euthanasia methods as per ethical guidelines.

8. Conclusion

This experiment helps in understanding the pharmacological modulation of GI motility by different drugs. It provides insights into their potential use in treating motility disorders such as constipation, diarrhea, and gastroparesis.

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