Question

Laxatives

•Actions

•Indications

•Pharmacokinetics

•Contraindications

•Caution

•Adverse Effects

•Drug-to-Drug Interactions

Antidiarrheal Drugs

•Actions

•Indications

•Pharmacokinetics

•Caution

•Contraindications

•Adverse Effects

•Drug-to-Drug Interactions

Phenothiazines

•Actions

•Indications

•Adverse Effects

Nonphenothiazines

•Actions

•Indications

•Adverse Effects

Substance P/Neurokinin 1 Receptor Antagonists

•Actions

•Indications

•Pharmacokinetics

•Adverse Effects

Answer 1

1) Laxatives

• Actions

1. Bulk forming - Absorb water into the feces and increase bulk to produce large and soft stool.
2. Stimulants - stimulate the motility of large intestine.
3. Surfactant - Inhibit absorption of water so fecal mass remains large and soft.
4. Osmotics - Attract water into the large intestine to produce bulk and stimulate peristalsis.
5. Lubricants - Act to soften the feces,ease the strain of passing stool, and lessen irritation to hemorrhoids.

• Indications : Used to treat acute and c hronic constipation, irritable bowel syndrome, diverticulosis, softening fecal impaction.
• Pharmacokinetics : in general the laxatives absorbed minimally and excreted in large amount through feaces.
• Contraindications : Bowel obstruction.
• Caution : do no give laxatives to hypersensitive patient and patient with signs of appendicitis or inflamed bowel.
• Adverse Effects: Impaction, fluid overload, decreased absorption of vitamins, skin rashesabdominal bloating, rectal irritation, cramping, diarrhea, increased thirst, electrolyte imbalance.
• Drug-to-Drug Interactions: there can be some changes in the effect of laxative with other medicines and herbal products.

Antidiarrheal Drugs

• Actions :

1. Absorbant - coat the wall of the GI tract, binds to the causative bacteria or toxins which is then eliminated through feaces.
2. Antisecretory - reduce the secretion, reduce the intestinal muscle tone and peristalsis of GI tract
3. Antimotility drug- decrease bowel motility and relieve rectal spasm, decrease the transit time through the bowel allowing more time for water and electrolytes to be absorbed.

• Indications : Acute and chronic Diarrhea
• Pharmacokinetics:
• Caution: care should be taken when using antidiarrheals if the cause of diarrhea is bacterial as this allows the bacterial toxin to remain in body , excess use may cause contipation.
• Contraindications : Children less than 2 years of age, Risk of fatal Paralytic Ileus,Diarrhea associated with organism that may penetrate the gut wall such as E. coli, Salmonella, Symptomatic Pseudomembranous Colitis, Risk of toxin retention, Precipitate Toxic Megacolon, Hepatic failure, Precipitate Hepatic Encephalopathy
• Adverse Effects :  confusion, dizziness, skin rashes, tinitus, hearing loss, increased bleeding time, hypotension, constipation, dark stool, headache.
• Drug-to-Drug Interactions : If anti secretory anti diarrheals are administered together with Quinidine, Omeprazole, Ritonavir ;These are all CYP450 inhibitors which may elevate the plasma level of Loperamide to as high as 3 folds and enable Loperamide to pass the blood brain barrier and lead to sedative effects of Opioid agonists.

Phenothiazines

• Actions:

1. It blocks dopamine-1 (D1) and dopamine-2 (D2) receptors within the mesolimbic dopamine pathway which induce a state of tranquility, calmness, or to diminish anxiety or stress.
2. It can also block both histamine (H1) and cholinergic muscarinic receptors leading to sedation, suppression of oral secretions, tachycardia, urinary retention, and constipation.

• Indications : used to treat serious mental and emotional disorders, including schizophrenia and other psychotic disorders, Some are used also to control agitation in certain patients, severe nausea and vomiting, severe hiccups, and moderate to severe pain in some hospitalized patients.
• Adverse Effects: Constipation, trouble urinating, dryness of mouth, confusion, problems with memory, dizziness or fainting, drowsiness, trembling of the hands and fingers, and problems with muscle movement.