Antiprotozoal Agents

Antiprotozoal Agents

• Metronidazole (Flagyl) is used to treat protozoal infections.
• Mitazoxanide (Alinia) is in the same drug class as Metronidazole.
• Tinidazole (Tindamax) is also used to treat protozoal infections.
• Protozoal Infections can be caused by insect bites, specifically Malaria, Trypanosomiasis, and Leishmaniasis.
• Protozoal Infections can also be caused by Ingestion or Contact with the Causal Organism, such as Amebiasis, Giardiasis, and Trichomoniasis.
• Risk factors for Protozoal Infections include unsanitary, crowded conditions and poor hygienic practices.
• Atovaquone (Mepron) is especially effective against PCP.
• Metronidazole (Flagyl) is used to treat amebiasis, trichomoniasis, and giardiasis.
• Pentamidine (Pentam 300, NebuPent) is used to treat PCP, trypanosomiasis, and leishmaniasis.
• Tinidazole (Tindamax) treats trichomoniasis, giardiasis, and amebiasis.
• Benznidazole is administered for Pediatric patients with Chagas.
• Metronidazole (Flagyl) is an antibiotic that produces free radicals inside anaerobic bacteria and protozoans, leading to DNA damage and cell death.
• Metronidazole (Flagyl) treats Amebiasis, trichomoniasis, giardiasis, bacterial vaginosis, septicemia, endocarditis, rosacea, and bone/joint/lower respiratory tract infections.
• Trichomoniasis, amebiasis, and giardiasis are treated orally (PO).
• Anaerobic bacterial infections are treated intravenously (IV).
• Bacterial vaginosis and rosacea are treated topically.

Histamine-2 Antagonists

• Histamine-2 (H₂) Antagonists block the release of hydrochloric acid in response to gastrin.
• Cimetidine (Tagamet HB) is a Histamine-2 antagonists.
• Ranitidine (Zantac) is a Histamine-2 antagonists.
• Famotidine (Pepcid) is a Histamine-2 antagonists.
• Nizatidine (Axid) is a Histamine-2 antagonists.
• H2-antagonists selectively block histamine-2 receptor sites.
• Blockage of histamine-2 receptors leads to a decrease in gastric acid secretion and overall pepsin production.
• H2-antagonists are indicated for short-term treatment of active duodenal or benign gastric ulcers.
• Drug indications include treatment of pathological hypersecretory conditions such as Zollinger-Ellison syndrome.
• H2-antagonists prevent stress-induced ulcers and acute upper GI bleeding in critical patients,
• H2-antagonists treat erosive gastroesophageal reflux, heartburn, acid indigestion, and sour stomach (OTC preparations).
• H2-antagonists are readily absorbed after oral administration, metabolized in the liver, and excreted in urine.
• Contraindications include any known allergy.
• Caution is advised in pregnancy or lactation, and in patients with hepatic or renal dysfunction.
• Adverse effects of H2-antagonists can include GI and CNS effects, cardiac arrhythmias, and hypotension.
• Drug interactions can occur with warfarin, phenytoin, beta blockers, alcohol, quinidine, lidocaine, theophylline, chloroquine, benzodiazepines, nifedipine, pentoxifylline, tricyclics, procainamide, and carbamazepine.

Antacids

• Antacids'indications provides symptomatic relief of upset stomach associated with hyperacidity and hyperactivity.
• Antacids are inorganic chemicals that neutralize stomach acid.
• Sodium bicarbonate (Bell-ans) is an antacid.
• Calcium carbonate (Oystercal, Tums) is an antacid.
• Magnesium salts (Milk of Magnesia) is an antacid.
• Aluminum salts (Amphojel) is an antacid.
• They neutralize stomach acid through direct chemical reaction.
• Usage is not advised for conditions that can be exacerbated by electrolyte imbalance.
• GI obstruction is a contraindication.

Proton Pump Inhibitors

• Proton Pump Inhibitors (PPIs) suppress the secretion of hydrochloric acid into the lumen of the stomach.
• Omeprazole (Prilosec) is a PPI.
• Esomeprazole (Nexium) is a PPI.
• Lansoprazole (Prevacid) is a PPI.
• Dexlansoprazole (Kapidex) is a PPI.
• Pantoprazole (Protonix) is a PPI.
• Rabeprazole (Aciphex) is a PPI.
• PPIs act at specific secretory surface receptors to prevent the final step of acid production, thereby decreasing the level of acid in the stomach.
• They are typically prescribed for short-term treatment of active duodenal ulcers, GERD, erosive esophagitis, and benign active gastric disease.
• PPIs are also used for long-term treatment of pathological hypersecretory conditions.
• PPIs are acid labile, rapidly absorbed in the GI tract, and metabolized in the liver before being excreted in the urine.
• Contraindications include allergy, and caution is advised during pregnancy or lactation.
• Adverse effects of PPIs include CNS effects (dizziness, headache, asthenia, vertigo, insomnia, apathy), GI effects (diarrhea, abdominal pain, tongue atrophy), upper respiratory tract symptoms (cough, stuffy nose, hoarseness, epistaxis), and other effects (rash, alopecia, pruritus, dry skin, back pain, fever).

Laxatives

• Laxatives include castor oil (P) and senna (Senokot) (O).
• Bulk Stimulants include magnesium citrate (Citrate of Magnesia) (P) and lactulose (Constilac), polyethylene glycol (MiraLax) (O).
• Docusate (Colace) is a lubricant.
• Metoclopramide (Reglan) is a GI stimulant.
• Loperamide (Imodium) (P) and diphenoxylate with atropine (Lomotil) (O) are antidiarrheals.
• Alosetron (Lotronex) is a 5-HT antagonist.

Drugs Affecting GI Tract Motor Activity

• GI drugs can speed up or improve movement of intestinal contents when movement becomes sluggish (constipation).
• Certain drugs are know to increase the tone of the GI tract and stimulate motility throughout the system.
• Certain drugs are known to decrease movement along the GI tract when rapid movement decreases the time for absorption of nutrients (diarrhea).
• Chemical Stimulants act by chemically irritating the lining of the Gl tract.
• Bulk Stimulants increase fecal matter in bulk.
• Lubricants help the intestinal contents move more smoothly.
• Bisacodyl (Dulcolax) acts as a popular OTC chemical stimulant laxative.
• Cascara (Generic) a reliable agent that leads to intestinal evacuation.
• Castor Oil (Neoloid) aids in thorough evacuation of the intestine.
• Senna (Senokot) is identified as a reliable drug, similar to cascara and it is an OTC.
• Chemical stimulants begin working at the start of the small intestine and boost motility throughout the GI tract by irritating the nerve plexus.
• These stimulants are absorbed at a slow rate and give off therapeutic effects when directly in the GI tract.
• Contraindications for chemical stimulants consists of allergy & acute abdominal disorders.
• Use chemical stimulants with caution for heart block, CAD, debilitation plus pregnancy and lactation
• GI effects: include diarrhea, abdominal cramping, nausea
• CNS effects: include dizziness, headache, weakness
• Side effects: include sweating, palpitations, flushing, fainting
• Castor oil can block absorption of fats and fat-soluble vitamins.
• Prototype chemical stimulant laxatives have drug interactions with other prescribed medications.
• Methylcellulose (Citrucel), Polycarbophil (FiberCon), and Psyllium (Metamucil) are bulk stimulants.
• Bulk stimulants increase motility by increasing the size of fecal material, which increases fluid in the GI tract, causes more stretch, stimulates local stretch receptors, and activates local GI activity. Volume administration is oral and is typically not absorbed systemically.

GI Stimulants and Antidiarrheals

• Lubricating G.I. medications includes Docusate (Colace) & Glycerin (Sani-Supp)
• Docusate softens intestinal bolus with detergent action; Glycerin, as hyperosmolar laxative, gently evacuates the rectum .
• Mineral oil (Agoral) form slippery coating in contents of intestinal tract, reducing water absorption & excreted in feces.
• Not systemically absorbed.
• Caution needed for heart block, CAD, debilitation, pregnancy & lactation.
• Side effects for lubricants include diarrhea, abdominal cramping and / mineral -oil causing -leakage, staining and hindering fat vitamin A, D, E & K
• Dexpanthenol (Ilopan) increases acetylcholine levels, stimulating the parasympathetic system, whereas Metoclopramide (Reglan) blocks dopamine receptors and makes GI cells more sensitive to acetylcholine
• These ultimately ramps up G.I. activity & the process of digestion through the upper GIT tract.
• Actions involves stimulating the Gl tract and increases secretion through rapidly absorption, liver metabolism & excretion in urine; Avoid with GIT obstruction & caution for pregnancy
• Negative issues consist of side impact: nausea, diarrhea, spasms. Check Digoxin and cyclosporine. Be careful with pregnancy, obstruction and heart / body systems.
• Bismuth Subsalicylate (Pepto-Bismol) coats Gl tract, soothing irritation and reducing excessive diarrhea by Crofelemer (Fulyzaq) useful against HIV / AIDS medication .
• Loperamide (Imodium) directly impacts muscles to slow absorption; While Opium Derivatives cause intestinal spasming for transit.
• Actions slows with a direct hit from the lining with relief towards both acute, chronic/ travellers.

Prototype Summaries

• Cimetidine is a Histamine-2 antagonist that inhibits histamine at H2 receptor sites of the stomach, reducing gastric acid secretion and total pepsin output.
• Sodium Bicarbonate provides symptomatic relief of upset stomach from hyperacidity. It is indicated for prophylactically to assist with GI bleeding and ulcer treatment.
• Omeprazole is a prototype Proton Pump Inhibitor known to inhibit the H+/K+ ATPase enzyme, reducing gastric acid production.
• Castor Oil is known to stimulate the movement of the intestinal wall and is used to remove poison, as used from the GI tract; acts by increasing movement.
• Mineral Oil is known for short term relief. Metoclopramide promotes gastric relief through upper GIT motility.