GIT Pharmacology Flashcards
How many thick muscles does the stomach have and name them
Oblique muscle layer
Circular muscle layer
Longitudinal muscle layer
From inside to outside
They’re involved in the peristaltic action
Name the parts of the stomach
The sphincters
Pyloric sphincter
Oesophageal sphincter
Rugae (where the secretory cells of the stomach are)
When you cut a section through the stomach name the layers of the stomach coming from the outside and name the layers of cells that line the stomach in the rugae
Submucosa
mucosa
Muscularis
Cells that line the stomach internally: The mucous surface cell Mucous neck cell Parietal cell Chief cell Enteroendocrine cells
What are the functions of the cells that line the stomach
Mucous surface cell:
Secrete mucus
Mucous neck cell:
Secrete mucus
Parietal cell:
Secretes HCL
And intrinsic factor
Chief cell:
Secretes pepsinogen and gastric lipase
Enteroendocrine cell:
Secretes gastrin
Another name for chief cell and enteroendocrine cells are called respectively?
Zymogenic cells
G cells
What is the pH of HCL
1-2
Importance of the stomach secretions
The mucus forms a protective barrier against corrosive secretions
Hydrochloric acid converts pepsinogen from chief cell to pepsin(pepsin is involved in digestion)
–
Intrinsic factor-absorption of vitamin B12 for RBC production (even if you eat lots of vit b12 foods without the intrinsic factor it won’t be absorbed)
–
The acid and enzyme converts food into a thick semi-solid paste called chyme
–
Gastrin hormone (G cell)
»release more gastric juice
»increase gastric motility
-relax pyloric sphincter
»constrict oesophageal sphincter preventing re-entry
(When food enters the oesophageal sphincter is constricted to prevent reflux and pyloric is relaxed for food to move into the small intestine)
What is the mucosal defense against acid and enzyme attack:
- The mucus barrier (500 m thick),
- a mucus matrix into which bicarbonate ions are secreted to produce a buffering gradient.(acts as a buffer as in base acid reaction to neutralize HCL)
3.The surface epithelium, which requires prostaglandins E2 and I2 synthesized by the gastric mucosa,
a.stimulate mucus and bicarbonate secretion,
b.decrease acid secretion and cause vasodilatation,
• all of which serve to protect the stomach against damage.(the prostaglandins do that)
NSAIDS which inhibit prostaglandin (PG) synthesis will
decrease the protective barrier
True or false and why
True
They inhibit cyclooxygenase (Cox)
In case of tissue injury membrane phospholipids are acted on by phospholipase
This converts membrane phospholipids toarachnid onset acid and these are converted to prostaglandins by Cox 2
This causes pain ,inflammation. This only comes when you’re injured
In the system there’s constitutive prostaglandins secreted in the absence of injury by Cox 1
NSAIDS usually inhibit Cox cuz the NSAIDS used are non selective and inhibit both Cox 1 and Cox 2 and causes ulcer when used for a long time so the selective Cox inhibitors are to be used(celecoxib)(check spelling)
What is peptic ulcer and what can it lead to if care is not taken
Peptic ulceration results from a breach in the mucosa lining of the alimentary tract caused by acid and enzyme attack.
•Unprotected mucosa rapidly undergoes auto-digestion(pepsin will digest the proteins in the surface lining of the stomach (enzyme attack))leading to a range of damage:
–Inflammation or gastritis
–Necrosis
–Haemorrhage
–Perforation as the erosion deepens(can cause leaking from stomach into peritoneum and that section of the stomach affected could be taken off causing a short transit time for food)
Note: Gastric and duodenal ulcers differ in their location but
present with similar symptoms and are treated on similar
principles.
What happens in GERD or GORD
When food is eaten and gets into the stomach there’s so much intrabdominal pressure so the food tries to come out. The lower oesophageal sphincter (los)closed to prevent food from coming out.
In some people the los is not strong enough to prevent the food from coming out.the stomach is lined w mucus to oreotect it from the corrosive substances but the oesophagus is not lined w that mucus so when the food mixed with HCL and enzymes is refluxed or comes up there is inflammation of the oesophageal lining and is felt as heartburn
It is not to be mistaken with a cardiovascular problem or cardio chest pain
What are the main causes of GORD
Loss of tone
Intraabdominal pressure caused by weight gain
Drug management of GORD is similar to that of acid-related disorders
True or false
•
True
Name three conservative treatment options of GORD
Conservative treatment options:
–Weight loss
–Raising the head of the patients bed
–Excessive smoking should be avoided
In three short sentences name the pathogenesis of PUD
-Increased hydrochloric acid secretion
●Inadequate mucosal defence against gastric acid
●Infection with gram-negative Helicobacter pylori
NB- know the cause of the PUD before you treat it
What are the four aims of treating PUD ,how is gastric acid secretion neutralized, how is mucosal resistance increased ?
To reduce gastric acid secretion with
Neutralizing secreted gastric acid secretion with Antacids such as
•
Increase mucosal resistance to acid-pepsin attacks with
Misoprostol or chelates(Bismuth chelate reduces mucosal damage or strengthens or repairs the mucosal layer)
•Eradicating H.pylori
How does gastric acid secretion occur and how is it reduced
Gastrin is released by G cells and this activates gastrin receptors on the mast cells to activate histamine and histamine activated histamine receptors on the parietal cells to cause Hplus release and the gastrin also activated gastrin receptors on the parietal cells to cause the HPlus release
Proton pump inhibitors to stop the release of Hplus
»H2 antagonists
»Muscarinic receptor antagonists
How does H pylori cause PUD and how is it eradicated
H pylori causes increased gastrin release by the G cells
Gastrin can directly activate the gastrin receptors on parietal cells and can also activate gastrin receptors on mast cells causing release of histamine causing the activation of histamine receptors on parietal cells causing release of Protons and chlorides
When the test is done is Hpylori is involved
Triple therapy is used :
One proton pump inhibitor and two antibiotics namely metronidazole and amoxicillin or metronidazole and clarithromycin or amoxicillin and clarithromycin. Takes a week or two to work
Or Quadruple therapy:
One proton pump inhibitor ,two antibiotics and bismuth chelate
More effective than triple therapy and takes shorter time to work like three days or one week
What system does the parietal cell use to cause the release of H plus and what drugs inhibits it,what’s the mechanism of action , route of administration,indications ,adverse effects ,contraindications and the function of clopidogrel
Proton pump or Hydrogen potassium ATPase
It pumps protons
Omeprazole,Iansoprazole ,Esomeprazole,Rabeprazole,Lansoprazole
They are proton pump inhibitors
Mechanism of action: They inactivate the ATPase
And cause irreversible inhibition of the hydrogen /potassium ATPAse
Route of administration- oral and Occasionally Iv
Indications-Indications: short term treatment of peptic ulcers, eradication of H. pylori
- Adverse effects: GI upsets, nausea, headaches, PPIs may increase the risk of fractures, particularly if the duration of use is 1 year or greater
- Contraindications: PPIs(proton pump inhibitors may decrease the effectiveness of clopidogrel (used in place of aspirin at a low dose of 75 milligram for its anti platelet activity and is given to people at risk of stroke or thrombosis also in case some people can’t take aspirin due to some disease they take clopidogrel)because they inhibit CYP2C19 and prevent the conversion of clopidogrel to its active metabolite.
When a certain mechanism is used and brings in Chloride what does it take out and later chloride is taken out with what
Bicarbonate
It’s taken out with potassium
Name the receptors on the parietal cell
Gastrin receptors(G receptors)
Histamine H2 receptors
Muscarinic receptors
Prostaglandin receptors(PGE2)(the prostaglandins inhibit the release of H plus from the parietal cell or decrease the release of Hplus and Chloride
Where is histamine released from and which drugs inhibit histamine receptors ,mechanism of action,route of administration,indications,adverse effects,contraindications
Mast cells
Cimetidine (Tagamet)(it is a hepatic enzyme inhibitor meaning it stops the metabolism or inactivation of warfarin ,phenytoin)
Ranitidine (Zantac)
Famotidine
Nizatidine
They are histamine H2 receptor antagonists
Mechanism of Action: Competitively block the action of histamine on the parietal cells by antagonizing H2 receptors.
- Route of administration: oral and IV
- Indications: Treatment of peptic ulcer and GORD
- Adverse effect: Diarrhoea, dizziness, muscle pains, alopecia, transient rashes, confusion in the elderly and hypergastrinaemia,
- Cimetidine causes low sperm count due to its anti-androgen effects, gynaecomastia & impotence due to its modest affinity for androgen receptors.
•Contraindications: Cimetidine (hepatic enzyme inhibitor) not given to patients stabilized on warfarin, phenytoin and theophylline(given to asthmatic patients).(these three drugs have narrow therapeutic index)
How does vagus nerve cause the release of protons and chloride ,what drugs inhibits the muscarinic receptors,mechanism of action,route of administration,indications and adverse effects
Vagus nerve connects stomach to brain so when you sense food the vagus nerve activates themuscarinic receptors on the mast cells and activates the muscarinic receptors on the parietal cells using acetylcholine
Muscarinic receptor antagonists
•Examples: Atropine, pirenzepine, propantheline, dicyclomine (dicycloverine)
- Mechanism of Action: (The main effects of parasympathetic activity on the GIT are increased motility and increased secretory activity).
- Inhibition of parasympathetic activity, causing relaxation of GI smooth muscle may be of value in peptic ulcer since the condition may be accompanied by increased muscle spasm and reduces secretions of HCL
- Route of administration: oral or I.M.
- Indications: As adjuncts in the management of peptic ulcer(usually aren’t used but in some severe conditions they are used)
Adverse effects: Constipation due to reduced GI motility
How does misoprostol work ,mechanism of action,route of administration,contraindications,adverse effects
It’s an analogue (similar)of the PGE2
It activates prostaglandins receptors to cause the inhibition of the release of Hplus
Mucosal strengthener
Examples: Misoprostol (cytotec)
- Mechanism of action: Synthetic analogue of PG E1, imitating the action of endogenous PGE2 and PGI2, thereby maintaining the integrity of the gastroduodenal barrier.
- It therefore promotes healing by exerting a direct action on the ECL cell (and possibly parietal cell), inhibiting the basal secretion of gastric acid.
- It also increases mucosal blood flow and augments the secretion of mucus and bicarbonate
- Route of administration: oral
- Indications: Ulcer healing and prophylaxis with NSAID use(if you don’t have a choice to give non selective NSAID for use for a long time then you give misoprostol to prevent the person from getting ulcer)
- Contraindications: Hypotension, pregnant and breast-feeding women,causes abortion
- Adverse effects: Diarrhoea, nausea and abdominal pain
Ameritech is a combination of diclofenac and misoprostol to help the person
Can cause abortion
Name three antacids and they’re mechanism of action in PUD ,indications,adverse effects and how the adverse effects occur and contraindications
Antacids
Examples: Aluminium hydroxide, magnesium hydroxide ,sodium bicarbonate,tricilicate ,milk of magnesia
They consists of alkaline either aluminum,magnesium or sodium salts and are used to 1. raise the luminal pH of the stomach to stop pepsin from working and 2.when it’s raised they neutralize the acid and 1.(part of 1)reduce the damaging effect of pepsin which is pH dependent
Pepsin acts as a certain pH so it is not able to work for auto digestion to occur
3.These salts are heavy metals and can bind to pepsin to inactivate it
Indications- symptomatic relief of GORD and ulcers
Adverse effect-constipation and diarrhea ,belching,farting
Antacids with aluminum cause constipation and those with magnesium cause diarrhea
Nugel is a mixture of aluminum hydroxide and magnesium hydroxide to stop the diarrhea and prevent constipation
Sodium bicarbonate with HCL forms salt,water and carbon dioxide causing people to fart and belch
Not to be given to those with hypertension cuz of the salt
It shouldn’t be within two hours of giving antibiotics and anti Fungals cuz antacids have heavy metals which form complexes w the drugs and inactivates the drugs
What is the mechanism of action of sucralfate or carafate which is used to treat PUD,Indications,side effects,contraindications,
Can be used to prevent & treat PUD
•It is a complex of aluminium hydroxide and sulfated sucrose, which releases aluminium in the presence of acid.
•The residual complex carries a strong negative charge which binds to cationic groups in proteins to forms sticky polymer in acidic environment (pH <4) and adheres to the ulcer site, forming a barrier to cover the ulcers in the stomach lining
•This action restricts further caustic damage and stimulates mucosal prostaglandin and bicarbonate secretion from gastric mucosa.
Contraindications-May bind with other drugs and interfere with absorption of fluoroquinolone antibiotics, theophylline, tetracycline, digoxin and amitriptyline.
•Give approximately 2 hours before or after other drugs
•Take on an empty stomach before meals so that the food won’t cover the ulcer sites
Adverse effects: It may cause constipation, dry mouth, nausea, vomiting, headache
Mechanism of action of bismuth compounds,adverse effects,Indications,contraindications
Two bismuth compounds are available: bismuth subsalicylate and bismuth subcitrate potassium
•Bismuth coats ulcers and erosions, creating a protective layer against acid and pepsin.
•It may also stimulate prostaglandin, mucus, and bicarbonate secretion.
•Some activity against H. pylori
•Should not be used repeatedly or for more than 2 months at a time
•Can cause black stools and tongues, constipation
•Prolonged usage of some bismuth compounds may rarely lead to bismuth toxicity, resulting in ataxia,headache,confusion,seizures
Mechanism of action of alginates ,route of administration,indications,contraindications
Examples: Gaviscone ( is an alginate containing antacid)
- Mechanism of action: Forms an impenetrable raft that floats on the surface of the gastric contents. The layer prevents gastric acid from refluxing into the oesophagus.
- Route of administration: oral
- Indications: useful in GORD
- Contraindications: Well tolerated but no effect upon acid secretion or healing
No serious side effects
What is nausea and vomiting
Nausea
–an unpleasant feeling in the upper abdomen and throat which usually precedes vomiting.
–May be experienced without vomiting.
Vomiting
– Vomiting is the forceful evacuation of gastric contents through the mouth.
The higher centers (cerebral cortex)are involved in critical thinking true or false
True
CTZ and vomiting Centre are in the medulla oblongata true or false
True
Labyrinth is divided into two name em
Cochlear that controls sound that gets to the brain
Vestibular apparatus that is made up of fluid like mechanisms and control balancing
Has a strong communication with the vomiting Centre
Name the four mechanisms that cause vomiting
1.Disorienting motion (such as spinning around plenty)disturbs the labyrinth specifically the vestibular nuclei and this communicates to the vomiting Centre in the medulla
- Unpleasant emotions or experiences or emotional experiences will communicate to the higher centers in the cerebral cortex and will communicate w the vomiting Centre in the medulla to cause vomiting
- CTZ in the area postrema is triggered by toxins and drugs and when it is triggered it communicates w the vomiting Centre to cause vomiting by triggering the GIt muscles involved in vomiting to cause the forceful evacuation of gastric contents
- (the periphery)Stimuli to the pharynx or stomach via the vagus nerve and nucleus of the solitary tract and this communicates w the vomiting Centre to cause vomiting
Name the drugs that inhibit each of the four mechanisms that cause vomiting
- Hyoscine,Atropine,Scopolamine that block M1 receptors
Antihistamines such as promethazine,cyclizine ,meclizine ,cinnarizine to block H1 receptors(not to be mixed w H2 receptors in ulcer)
3.
Domperidone ,metoclopramide,chlorpromazine,prochlorperazine,
And they inhibit dopamine receptors (D2)
4.Ondansetron,dolasetron,granisetron,tropisetron, these are serotonergic receptor blockers in both CTZ and GIT
What receptors are in both the vestibular nuclei and vomiting Centre,receptors in the GIT and GIT muscles ,receptors in the CTZ
H1recptors (histamine receptors) M1 receptors(muscarinic receptors)
5-HT3(subscript 3)(serotonergic receptors)
These are also found in the CTZ
(D2)Dopaminergic receptors are also in the CTZ and found in the vomiting Centre as well I think
You have to know what is causing the vomiting to give medication for it true or false
True
Scopolamine can be used as prophylaxis in those who travel plenty and have vomiting issues true or false
True
What is emesis and name one drug that is used for emesis
Inducing vomiting to rid the GIT of ingested exogenous toxins
Emetic drugs
•Ipechacuanha (from some kind of herbal formulation)
– given as a liquid causes gastric irritation resulting in emesis.
Name some antihistamine drugs,state the mechanism of action,route of administration,indications,adverse effects,caution
H1 receptor antagonists
Examples: - cinnarizine, cyclizine, meclizine and promethazine
–These are antiemetic antihistamines
–Have little effect on nausea and vomiting induced by substances acting directly on the CTZ
–Are however effective in motion sickness and vestibular disorders.
Route of administration: cyclizine-oral, i.m, i.v; Cinnarizine-oral
Indications: motion sickness, vestibular disorders
Adverse effects: drowsiness, dry mouth, blurred vision
Caution: use with caution in urinary retention
Antipsychotics specifically the phenothiazines act on dopaminergic receptors ,muscarinic receptors,histaminic receptors and can be used to stop vomiting. Name some antipsychotic drugs,mechanism of action,route of administration,indications,adverse effects,contraindications and how the contraindications occur
Examples: Phenothiazines – chlorpromazine, perphenazine, , prochlorperazine and trifluoperazine
- Mechanism of action: Numerous effects; They block dopaminergic, histaminic and muscarinic receptors.
- Route of administration: Oral, rectal and intramuscular
- Indications: Nausea, vomiting, vertigo, psychosis
- Contraindications: May exacerbate Parkinsonian symptoms. Cuz in Parkinsons there’s motion or movement problems and motion is controlled mainly by dopamine and Ach is also involved . Dopaminergic neurons are destroyed so there a re few levels of dopamine. If you give antipsychotics they’ll block dopamine receptors reducing dopamine effects making things worse in the patient
•Adverse effects: sedation, extrapyramidal symptoms including dystonias and tardive dyskinesia .
These are symptoms of Parkinson’s
•Other antipsychotics, such as haloperidol also act as D2 antagonists in the CTZ and can be used for acute chemotherapy-induced emesi
Antipsychotics cross the blood brain barrier
The CTZ is located outside the blood brain barrier
Name dopamine antagonists,mechanism of action,route,indications,adverse effects,contraindications
Dopamine antagonists
•Examples: Domperidone (Motilium); metoclopramide (Maxolon)
- Mechanism of action: They block dopamine receptors in the CTZ. Their antiemetic effect is enhanced by promoting gastric emptying and small intestine peristalsis.
- Route of administration: Metoclopramide-oral, i.m, i.v, Domperidone-oral, rectal
- Indications: Nausea and vomiting
- Cautions:
- Metoclopramide produces a number of unwanted effects including disorders of movement (more common in children and young adults), fatigue, motor restlessness, spasmodic torticollis (involuntary twisting of the neck) and occulogyric crises (involuntary upward eye movements).
- It stimulates prolactin release causing galactorrhoea and disorders of menstruation.(these drugs can be given to people who don’t produce milk I mean nursing mothers to stimulate the prolactin release )
- Domperidone does not readily penetrate the blood-brain barrier and is consequently less prone to produce central side effects
Name some serotonergic receptor antagonists,mechanism of action,route,indications,adverse,contraindications
Selective 5-HT3 receptor antagonists
- Examples: ondansetron, granisetron, tropisetron, palonosetron and dolasetron
- Mechanism of action: Antagonism of 5-HT3 (serotonin) receptor in the CTZ is believed to be responsible for the antiemetic effects
- Route of administration: oral, rectal, intramuscular, iv
- Indications: Nausea & vomiting especially associated with cytotoxic therapy
- Adverse effects: Constipation & headache
Name three other classes of drugs that inhibit vomiting and examples of drugs under them
Cannabinoids –Nabilone (Synthetic cannabinol derivative) •Steroids –Eg. Dexamethasone •Neurokinin-1 antagonists –Aprepitant –fosaprepitant
Name the four classes of drugs used for their effects on the GI motility
Motility stimulants
–Antispamodics
–Laxatives
–Antidiarrhoeals
What is the importance of motility stimulants and examples
These are agents that increase GI motility without a laxative effect and
are used clinically for motility disorders such as:
–Gastric stasis (slow stomach emptying)
–Diagnostics e.g. Duodenal intubation
•Examples: Domperidone and metoclopramide increase intestinal motility
Name the classes of drugs used in antispasmodics ,examples in each class and the uses of antispasmodics
Antimuscarinics e.g. propantheline, dicycloverine (dicyclomine)(will worsen diarrhea)
They reduce GIT motility
To help stop spasms during period that causes pain (buscopan (drug) (hyoscine butyl bromide )
–Drugs acting directly on smooth muscle eg. Mebeverine, alverine, peppermint oil
•Antispasmodics have smooth muscle relaxant properties, therefore useful as adjuncts for:
–Non-ulcer dyspepsia(relax the muscles in ulcer to reduce pain kakra)
–Irritable bowel syndrome
–Diverticular disease
Name examples of anitmuscarinics ,mechanism of actions,adverse effects,indications,contraindications ,route of administration
Antimuscarinics
Example: propantheline, dicycloverine (dicyclomine)
Mechanism of action: Inhibition of parasympathetic activity
Causing relaxation of GI smooth muscle
Route of administration: oral
Indications: Non- ulcer dyspepsia, irritable bowel syndrome and diverticular disease.
Contraindications: Antimuscarinic drugs relax the LOS therefore should be avoided in GORD, also myasthenia gravis(check this)
Adverse effects: dry mouth, blurred vision, dry skin, tachycardia, urinary retention
Name examples of drugs that act directly on the smooth muscle ,mechanism of action,indications,route,
Drugs acting directly on smooth muscle
- Example: Mebeverine, alverine, Peppermint oil
- Mechanism of action: Direct relaxants of smooth muscle
- Route of administration: oral
- Indications: irritable bowel syndrome, diverticular disease
Name four causes of diarrhea and three causes of constipation
Constipation-reduced fluids,increased solids volume,decreased peristalsis(this can be due to drugs side effects example of such drugs are opioids,anticholinergics or antimuscarinics
Diarrhea-malabsorption,osmoticimbalance or osmotic load(absorption relies on osmosis so if gastric contents do not allow for osmosis to occur so it’ll stay in the GiT and will have to come out in diarrhea) so the malabsorption and increased osmotic load or the osmotic imbalance will cause an increase in fluid volume causing diarrhea
- Some antibacterials can induce diarrhea and some drugs can cause increased peristalsis causing diarrhea
- Virus/bacteria(acute) can cause diarrhea due to the toxins they produce example cholera causing increased fluid secretion this increases fluid volume causing diarrhea
- an underlying disease and when there’s anxiety can have an effect on the parasympathetic or enteric nervous system and this causes increased peristalsis causing diarrhea
Drugs used in cases of diarrhea are called ?
Costives
What are laxatives ,when are they given and what classes of laxatives are there
are drugs used to hasten transit time in the gut and encourage defecation.
–They are useful to prevent undue straining at stool.
Laxatives/purgatives may be given to:
–To remove poisons from the alimentary canal
–Prepare patients for radiological examination of the colon
–Remove parasites from the body after anthelminitic therapy sometimes when you give dewormers they paralyze the bacteria o you take in laxative to make em get out
–Empty the bowel before surgery
Classification of laxatives
–Bulk-forming laxatives eg. Bran, methylcellulose, Ispaghula husk
–Osmotic laxatives eg. Lactulose and saline purgatives
–Stimulant laxatives eg. Senna, danthron, bisacodyl, sodium picosulphate, castor oil
–Faecal softners (lubricants) eg. Liqiud paraffin, docusate sodium
Name examples of bulk forming laxatives ,mechanism of actions.,route of administration,indications,contraindications ,adverse effects
Bulk forming laxatives
Examples; Bran, methylcellulose, Ispaghula husk
Mechanism of action: They are fibres that absorb water and add up to the bowel contents thereby increasing the volume of non-absorbable solid residue in the gut, causing distending of the colon and stimulating peristalsis
Route of administration: oral
Indications: constipation
Contraindications: intestinal obstruction, colonic atony, dysphagia
Adverse effects: flatulence, abdominal distension, GI obstruction
Note: adequate fluid intake is encouraged, onset may be several days
Name examples of osmotic laxatives ,mechanism of actions.,route of administration,indications,contraindications ,adverse effects
Osmotic laxatives
Example: Lactulose and saline purgatives(can be salt in water)
Mechanism of action:
–Poorly absorbed substances that increase the water content of the bowel by osmosis(there is drawing of water from the system into the GIT where the feces are
–Lactulose, a semi-synthetic disaccharide not absorbed from the GIT.
–Magnesium and sodium salts are poorly absorbed and can be osmotically active.
Route of administration: oral
Indications: constipation,
Contraindications: intestinal obstruction,
Name examples of stimulant laxatives,mechanism of action ,indications, adverse effects,contraindications
Stimulant laxatives
Examples:
– Senna, danthron, bisacodyl, sodium picosulphate, castor oil
Mechanism of action:
–Increase GI peristalsis and water and electrolyte secretion by the mucosa possibly by stimulating enteric nerves
Route of administration: Oral and rectal
Indications:
–constipation and bowel evacuation prior to medical/surgical procedures
Contraindications:
–Intestinal obstruction
Adverse effects:
– intestinal cramps, possible damage to nerve plexi leading to deterioration of intestinal function and atonic colon. Danthron, potentially carcinogenic.
•Note: Give stimulant laxatives for short periods only
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Name examples of lubricants or (fecal softeners)laxatives,mechanism of action ,indications, adverse effects,contraindications
Lubricants (faecal softeners)
Examples Faecal softners (lubricants) eg. Liqiud paraffin, docusate sodium
Mechanism of action
Promote defaecation by softening (Docusate sodium) and/or by lubricating (liqiud paraffin) faeces to aid their passage through the GI tract.
Route of administration: oral, docusate sodium can be given rectally.
Indications: constipation, haemorrhoids
Contraindications: not in children less than 3 years
Adverse effects: Prolonged use of liquid paraffin impairs the
absorption of fat-soluble vitamin A and D
Note: Prolonged use not recommended.
Define diarrhea and it’s causes
Diarrhoea is defined as passage of frequent, loose, watery stools 3 or more times a day.
Causes of diarrhoea:
–Toxins
–Food
–Anxiety
–Drugs (e.g. Penicillins, laxatives, NSAIDS)
–Infections (amoebic dysentery, Typhoid, Cholera)
Name the ways diarrhea is treated
Treatment of Diarrhoea
There are four approaches to the treatment of severe acute diarrhoea:
- Maintenance of fluid and electrolyte balance through Oral Rehydration Therapy (ORT).
- Use of anti-microbial drugs
- Use of opiate-like anti-motility drugs
- Use of stool modifiers and adsorbents
NB-make sure you know the cause of the diarrhea before you treat w 2,3 or 4 but1 is standard
Which treatment of diarrhea is the first priority treatment ,what should it contain
ORT Should be the first priority in the treatment of acute diarrhoea
•Standard ORT should contain:
–NaCl
–KCl
–Sodium citrate
–Glucose
(in appropriate concentrations)
IV rehydration therapy recommended if dehydration is severe.
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What therapy for diarrhea is used when pathogens are confirmed to be the cause,what risks does it carry,acute diarrhea is usually self limiting true or false
Antimicrobial therapy is recommended only when a pathogen is identified or suspected.
•Acute infectious diarrhoea is self-limiting
•Note: Antibiotic therapy carries certain risks
–Resistance
–Destroying normal commensal flora
–Overgrowth of Clostridium difficile - pseudomembranous colitis
Antibiotic treatment is indicated in:
•Severe Cholera or Salmonella typhimurium infection- Tetracycline
- Shigella species infections - Ampicillin
- Campylobacter jejuni - Erythromycin or Ciprofloxacin
What does tetracycline,ampicillin and erythromycin or ciproflaxin
Severe Cholera or Salmonella typhimurium infection- Tetracycline
- Shigella species infections - Ampicillin
- Campylobacter jejuni - Erythromycin or Ciprofloxacin
What treatment is given for diarrhea when you are sure no poison,pathogen is causing It,state the class of drugs it is in,mechanism of action ,indications,contraindications
Costives
Class-Opiate-like anti-motility drugs
Examples: Loperamide & Codeine,morphine causes constipation and is an opioid as well as heroine
Mechanism of action: These act on opiate receptors in the myenteric plexus, which increases the tone and rhythmic contraction of the intestine, but lessens propulsive activity. (Decrease in propulsive activity leads to an increase in transit time and hence absorption of electrolyte. Overall effect is constipation. Loperamide and codeine also have an anti-secretory action)
Route of administration: Oral
Indications: As adjunctive therapy in some chronic diarrhoeal conditions. Have a limited role as an adjunct to fluid and electrolyte replacement in acute diarrhoea.
Increase transit time of food
Contraindications: Acute ulcerative colitis or antibiotic associated colitis. Not recommended for children.
Adverse effects: nausea, vomiting, abdominal cramps, constipation, drowsiness
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Name examples of stool modifiers ,mechanism of action, indications, contraindications
Stool modifiers/adsorbents
Examples: Kaolin, chalk, charcoal, methylcellulose & pectin
Mechanism of Action: Adsorption of toxins or coating and protecting the intestinal mucosa. They also add solid matter to the colonic contents and improve the consistency of the faeces.
Route of administration: Oral
Contraindications: Not recommended for acute diarrhoea
Adverse effects: inhibit the absorption of other drugs
Name five other classes of costives with examples
CONSTIPATION (COSTIVES)
–Morphine and its congeners
–Aluminium salts
–Atropine and other antagonists of muscarinic receptors
–Sympathomimetic drugs - Adrenaline, Ephedrine, Phenylephrine
–Phenothiazines - Chlropromazine
–Tricyclic anti-depressants – Amitriptyline & imipramine
(central impairment of parasympathetic reflexes)
What is IBd,the classification of IBD and four broad treatment of IBD
INFLAMMATORY BOWEL DISEASE (IBD)
Fall into two categories, but share a number of features. Symptoms often relapse and remit and their aetiology remains unclear.
Crohn’s disease: Affects the entire gut and inflammation occurs through out the full thickness of the bowel wall
Ulcerative colitis: Affects only the large bowel and inflammation is limited
to the bowel mucosa or a small part of the bowel
Treatment involves:
•Pharmacological
- Psychological support
- Correction of nutritional deficiencies
- Surgical resection
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What is the drug management of IBD and what is the aim
Controlling the inflammation and bringing about remission
Drugs used include:
•Glucocorticoids-have anti inflammatory properties
- Aminosalicylates-have anti inflammatory properties
- Immunosuppressives-suppress the immune system cuz inflammation is part of the immune response
- Cytotoxics and antibiotics-
Name examples of glucocorticoids,general mechanism of action(not in details), indications, contraindications, adverse effects
Glucocorticoids
Examples: Prednisolone, budesonide, hydrocortisone,Dexacortine(check?)
Mechanism of Action: They have anti-inflammatory effects
Route of administration: rectal, enemas, suppository or foams in localized disease. Oral or i.v. in extensive or severe disease
Indications: for acute relapses of IBD
Contraindications: bowel obstruction or perforation or for long periods
Adverse effects: Cushing’s syndrome-obesity and ‘moon’ face, hyperglycaemia, hypertension,osteoporosis, muscle weakness and wasting, suppression of growth in children
Name examples of aminosalicylates,general mechanism of action(not in details), indications, contraindications, adverse effects
Aminosalicylates
Examples: Sulfasalazine, Mesalazine, Olsalazine
sulfasalazine, broken down in the gut5-aminosalicylate (5-ASA)
-and sulphapyridine which acts as a vehicle to transport the drug to the colon
Mechanism of action: One proposed mechanism is the inhibition of prostaglandins, resulting in local anti-inflammatory effects in the colon.
Mesalazine = 5-ASA
Olsalazine = 2(5-ASA)
Route of administration: oral, rectal
Indications: maintenance therapy of IBD
Name examples ofimmunosuppressive,cytotoxic,antibiotics ,general mechanism of action(not in details), indications, contraindications, adverse effects
Immunosuppressives, cytotoxics, and antibiotics
Immunosuppressant azathioprine is used as an adjunct to other therapies when side effects of steroids are overwhelming.
In addition, cytotoxic drugs e.g. methotrexate, the antibiotic metronidazole have all been used to modulate the disease process
In treating diarrhea what isused to treat the travelers diarrhea
Agents that modify fluid and electrolyte transport
Bismuth subsalicylate, used for traveler’s diarrhea, decreases fluid secretion in the bowel. Its action may be due to its salicylate compo- nent as well as its coating action
