GIT Lec 3 Pt 6 - Irritants & Stimulants, Lubricants And Chloride-channel Agonists

Question 1

What are the subdivisions of stimulant and irritative laxatives?

Answer 1

1. Caster oil and diphenolmethane derivatives (phenolphthalein, sodium picosulfate and bisacodyl)
2. Anthraquinone derivatives (senna which acts in 8-10hrs, danthron which acts in 6-12 hours, cascara, aloes and rhubarb)

Question 2

What are the preparations available for Bisacodyl?

Answer 2

A. It can be effective when given orally; dosage 5-10mg
B. It can also be given as a suppository (5mg for children) and (10mg for adults); when given in this manner it acts with 20-60 minutes and in geriatric (elderly) patients it can replace regular enema

Question 3

what are the side effects of bisacodyl?

Answer 3

1.Abdominal cramps and the possibility for atonic colon when used chronically.
2. When given as suppositories, a burning sensation in the anus may occur along with mild proctitis.
3. Anal soreness due to suppository leakage has also been reported.
4. When given orally they should NOT be crushed or chewed to prevent gastric irritation.
5. They should NOT be given one hour before milk, or two hours before antacids, H2-blockers or PPI’s so early degradation of the enteric coat doesn’t occur resulting in gastric irritation and pain.

That’s why these medications should not be used for more than 10 consecutive days.

Question 4

What are the side effects of caster oil?

Answer 4

1. Abdominal colic
2. Water losses which leads to electrolyte imbalance
3. Chronic use may cause irritation of the intestinal mucosa.

Question 5

What are the contraindications of caster oil?

Answer 5

It initiates uterine contractions thereby should be avoided in pregnant women.

Question 6

What are the pharmacokinetics of Sodium Picosulfate?

Answer 6

1. Has effective laxative effects
2. Prompt onset of action
3. Colon-specific site of action which reduces water and electrolyte losses.
4. Good tolerability
5. Suitable for all age groups
6. Convenient single bed time dose

Question 7

What is the indication of sodium picosulfate?

Answer 7

It’s indicated for treating constipation in patients who have cardiovascular diseases, hernia, or are postoperative.
It’s also used for bowel-clearing before procedures like radiotherapy, endoscopy, labour and surgery.

Question 8

What are the side effects of sodium picosulfate?

Answer 8

Prolonged use or overuse may result in:
1. Diarrhea with excessive water and electrolyte losses, especially potassium.
2. It can also lead to atonic, non functioning colon.

Question 9

What are the pharmacokinetics of the anthraquinone-derived drug senna?

Answer 9

1. Senna is a widely used drug which acts in 8-10 hours.
2. It causes water and electrolyte secretion in the lumen
3. When combined with Docusate-containing medications, it can be used to treat opioid-induced constipation

Question 10

What are the side effects of Senna?

Answer 10

1. Nausea and vomiting
2. Diarrhea
3. Urine discoloration (yellowish brown to red)

Question 11

What are the contraindications of senna?

Answer 11

1. Lactating women
2. Intestinal obstruction
3. Electrolyte imbalance

Question 12

What is the MOA of lubricant laxatives?

Answer 12

Mineral oils and glycerin suppositories work by lubricating the intestines thereby facilitating the movement of hard feces.
Minerals should be taken orally in an upright position as to prevent tracheal aspiration of them which could lead to lipoid-aspiration pneumonia.

Question 13

What is the MOA of chloride-channel agonists?

Answer 13

Chloride-channel agonists like Lobeprostone work by increasing fluid secretion in the intestinal lumen.
The increased chloride secretion leads to softening of the feces and increased intestinal motility.

Question 14

What is the indication of Lobeprostone?

Answer 14

Chronic constipation

Question 15

What are some of the drugs used in chronic constipation?

Answer 15

1. Lobeprostone
2. Linaclotide
3. Plecanatide (guanylate cyclase agonist)