Wk2 Flashcards
(32 cards)
Pharmacokinetic properties (LADME)
Liberation: disintegration, dispersal, dissolution
Absorption: how’s it absorbed
Distribution: how does it spread through the body
Metabolism: is it turned chemically inside the body
Excretion: how is it eliminated form the body
Describe administration of medication the systemic effect
Most drugs given orally
Some changed by GI tract
Drugs absorbed by GIT pass through portal system to liver
Only once passed through liver can drug be distributed in systemic circulation
All this is known as oral bioavailability - titrating drugs bc differs form pt to pt
What are pharmacodynamics
The biochemical and physiological effects of drugs in the body Drug response Drug concentration vs effect Cellular response Modify cell function Competitive (reversed) No competitive (can't be reversed)
Information about the GI tract
Major endocrine systems of the body
Acid secreted by parietal cells
Maintains stomach acid at pH 1-4
Acid secretion stimulated by large, dfatty meals, excessive amounts of alcohol, emotional stress
What is the enteric nervous system
2 major nerve plexuses in wall of GIT
Sub mucosal and Myenteric
Meds to control gastric secretion
Antacids, histamine H2, proton pump
Meds to control motility
Purgatives, antidiarrhoeals, antispasmodics
Meds to control vomiting
Emetic, antiemetic
What are antacids
Don’t prevent overproduction of acid , neutralise acid once it’s in the stomach
Weak bases
Combine with HCL to raise pH
PH more than 4 = inactive pepsin (digestive protease enzyme released by chief cells that function to degrade food protein into peptides)
Types of antacids
Aluminium salts: constipation effects
Sodium bicarbonate: highly soluble, quick onset, short duration, issues with heart failure, renal issues, hypertension
Magnesium salts: laxative effects, dangerous in renal failure (accumulation of MG)
Calcium salts: may cause constipation
Siemthicone: reduce bloating, decrease surface tension of gas bubbles causing them to combine
Nursing considerations in use of antacids
May inactivate other drugs
Alteration of pH causes reduced drug absorption
Administer other drugs 2 hrs before or after
What is pharmacokinetics
Explores what the body does to the drug Mechanisms of absorption/distribution Rate of onset Action of drug Duration Effects Route of excretion
What are H2 antagonists
Histamine is a potent stimulant agent for acid production in the stomach
Acid secretion increased by H2 -receptor activation.
H2 Antagonists block the actions of histamine & reduce acid production
Reduce acid secretion
what are the side effect and nursing considerations of H2 antagonists
- Diarrhoea, constipation, headaches, dizziness
- Rarely hypotension, liver problems, clotting disorders
- Can interact with other drugs & reduce absorption
- Assess for allergies and impaired renal or liver function.
- Take 1 hour before or after antacids
- Ranitidine may be given intravenously; follow administration guidelinesH2 antagonists may be administered with or without food
- Assess effectiveness of medications relief from sysmptoms
Examples of H2 antagonists
Zantac (Ranitidine)
Tazac (Nizatidine)
Tagamet (Cimetidine)
Pepcid (Famotidine)
Gastric ulcer: 20% = H2 antagonist
Duodenal ulcer: 80% = H2 antagonist with or without h.pylori
what are PPI’s
The Proton Pump inhibitors block the release of acid
The parietal cells release hydrogen ions during HCl production.
• Hydrogen ion are referred to a “protons”
Parietal cells use an enzyme system “Proton pump” to manufacture & release acid into the stomach
The Proton Pump inhibitors block the release of acid
The parietal cells release hydrogen ions during HCl production.
• Hydrogen ion are referred to a “protons”
Parietal cells use an enzyme system “Proton pump” to manufacture & release acid into the stomach
Side effects and nursing considerations for PPI’s
• Assess for allergies and history of liver disease
• Pantoprazole is the only proton pump inhibitor available for parenteral administration
– can be used for patients who are unable to take oral medications
• May increase serum levels of diazepam, phenytoin, and cause increased chance for bleeding with warfarin
• Omeprazole: B4 meals, whole, with antacids, short term
Examples of PPI’s
Omeprazole (Somac), Pantoprazole Losec Nexium Prilosec Lansoprazole
– Short term treatment of active duodenal and benign gastric ulcers
– Maintenance therapy peptic ulcers, oesophigitis, gastric reflux
Examples of antacids
• Mylanta
(aluminum and magnesium)
• Quick-eze (calcium and magnesium carbonate)
• Gaviscon (simethicone)
What are antiemetics
used to prevent vomitingCentral neural regulation located in 2 separate medulla units (vomiting centre in the medulla which can be stimulated from GI tract via vagus nerve and chemoreceptor trigger zone (CTZ). CTZ sensitive to chemical stimuli and main site of many druges to prevent emesis
Main neurotransmitters that control vomiting include acteycholine, histamine, dopamine, serotonin and opioid and 5HT
What are the different types of antiemetics
Antimuscarinic: Used only for prevention or treatment of motion sickness, Action: thought to be on muscarinic receptors associated with the vestibular apparatus
Antihistamines: have antimuscarinic activity + antihistamine effects, Block histamine H1 receptors in vestibular apparatus (inner ear).
Also have additional sedative and anticholinergic properties that enhance antiemetic activity
Dopamine atagonists: Thought to bind to D2 receptors in the chemoreceptor trigger zone & vomiting centre
Serotonin 5-HT3 receptor antagonists: Central and peripheral 5-HT3 (Serotonin) receptor blockade in GI & CTZ centre
Side effects and nursing considerations of antiemetics
Dry mouth, thirst, blurred vision, drowsiness, constipation, urinary retention, restlessness, fatigue
Dopamine antagonists used with caution • Impaired cardiovascular function • Glaucoma • liver disease • Seizure disorder • GI obstruction
Examples of antiemetics
Antimuscarinic:
Kwells, travacalm
Antihistamines: Dimenhydrinate, Promethazine (Phenergen)
Dopamine atangonists: Metoclopramide (Maxalon)
Prochlorperazine (Stemetil)
• Domperidone (Motilium)
Serotonin: Ondansetron (Zofran) – Granisetron - expensive
What are antidiarrhoeals
help bowel motility in order to prevent diarrhoea (Increase in volume, fluidity or frequency of bowel movements, relative to the usual pattern for the person)
