Gastro Flashcards
What is the approximate height of villi?
1mm
What type of cells are 90% of the epithelial lining cells of the small intestine?
Enterocytes
Which enzyme breaks down sucrose and what are the products of the reaction?
Sucrase
Gives glucose and fructose
Which enzyme breaks down lactose and what are the products of the reaction?
Lactase
Gives glucose and galactose
Which enzyme breaks down maltose and what are the products of the reaction?
Maltase
Gives glucose and glucose
Which monosacccharides are transported into enterocytes by SGLT1?
Glucose
Galactose
How does the SGLT1 transporter work?
Sodium dependent, works via electrochemical gradient as small molecules cannot penetrate the apical layer alone
What transports fructose into enterocytes?
GLUT5
How do PEPT1 transporters work?
Proton dependent
How do hydrophilic drugs enter the enterocytes?
Absorption via uptake transporters
What transporters are involved in drug efflux?
P-glycoprotein
BCRP
Give examples of drug substrates for PEPT1.
Cephalosporins
Penicillins
Enalapril
Val-acyclovir
Give examples of drug substrates for OCTN2 (efflux).
Quinidine Verapamil Imatinib Valproic acid Val-acyclovir
Give examples of drug substrates for OATP2B1.
Pravastatin
Rosuvastatin
Atorvastatin
Fexofenadine
Give examples of drug substrates for P-gp (efflux).
Indinavir Tacrolimus Erthromycin Digoxin Verapamil Quinidine Imatinib
Define peptic ulcer
Breach in the continuity of the lining >5mm in diameter with associated inflammation
What are the aims of treatment of peptic ulcers?
Complete healing
Managing dyspepsia
Reflux symptoms
GORD
What is GORD?
Gastro-oesophageal reflux disorder
What are the symptoms are GORD?
Chronic heartburn
Pain
Nausea
What is GORD commonly associated with?
Chronic cough and laryngitis
Worsening asthma
What are the alarm features of GORD?
Anaemia Weight loss Anorexia Recurrent problems (>55 years) Malaena Haematemesis Swallowing problems
What are alginates?
Foaming agent that forms a raft above gastric contents to reduce reflux and protract oesophageal mucosa
What the common issues with magnesium and aluminium antacids?
Magnesium- laxative
Aluminium- constipation
What is the common excipient in antacids than can cause problems?
Sodium bicarbonate
What is the common issue with antacids?
Can impair absorption of drugs that are basic due to increased pH
When are H2 antagonists used in peptic ulcers?
Heal ulcers at high doses, used in NSAID prophylaxis and maintenance as well as GORD
When are PPIs used in GORD?
For 1-2 months at full dose and then at lowest dose in case of recurrence
What is misoprostol?
Prostaglandin analogue with antisecretory and cytoprotective effects. Promotes ulcer healing and protects from NSAID damage.
When should misoprostol be avoided?
Pregnancy
How is GORD treated in children?
Usually resolves itself by 12-18 months in infancy
Can use alginates or thickeners
H2 antagonists then PPI if persistent in older children
How is H. pylori detected?
Produces antibody that is detectable in serum, saliva or urine
What is the treatment process for NSAID associated peptic ulcers?
Assume it is due to H. pylori and discontinue NSAID use
PPI to promote rapid healing and reduce relapse
What bacteria is the most common cause of peptic ulcers?
H. pylori
What is achlorydia?
Common with long term use of PPI
Low gastric acid production associated with adverse events
What are the risks associated with long term use of PPIs?
Pneumonia Fracture risk Osteoporosis Reduced calcium absorption GI infection risk Mask GI cancer symptoms
Define diarrhoea.
Abnormal passing of loose/liquid stools at increased frequency/volume
Generally >70% water
What are the red flag symptoms of diarrhoea?
Unexplained weight loss Blood in stools Systemic illness Foreign travel Symptoms lasting over 1 week Severe pain
What are the common pathogens causing diarrhoea?
E. coli
Campylobacter
Salmonella
Shigella
What is the normal treatment for diarrhoea?
Oral rehydration to replace lost electrolytes
Formulated with dextrose and citrate/bicarbonate
What does loperamide do?
Increases salt and water reabsorption by reducing gut motility
What is the antidote for opioids?
Naloxone
Give examples of antispasmodics.
Meberverine
Dicyclomine
When is ciprofloxacin used in IBD?
Prophylaxis of infection from shigella/salmonella
Give an example of a probiotic?
Lactobacilli
What is racecadotril?
Oral enkephalinase inhibitor reducing hyper secretion of water and electrolytes into the gut lumen
What is kaolin?
Very low dose morphine used to bulk out stools
What is co-phenotrope?
Diphenoxylate and atropine
When is the rotavirus vaccine given?
Two doses at 2 and 3 months old
What is pseudomembranous colitis?
Caused by C. difficile and transmitted due to poor hygiene, often associated with antibiotic use
How is pseudomembranous colitis treated?
Metronidazole 400mg tds
Oral vancomycin 125mg qds
Used for 1-2 weeks and can be used together if no resolution
What is ulcerative colitis?
Inflammation of the mucosa of the rectum and colon
What is Crohn’s disease?
Patchy, transmural inflammation of the entire gastrointestinal tract
How is IBS managed?
Corticosteroids
Mild- enemas, suppositories
Diffuse disease- oral aminosalicylate
Severe- hospitalisation, IV corticosteroid and immunosuppressants
What is sulphasalazine?
Medication used in IBS with no response to local therapy to maintain remission
What are the side effects of sulphasalazine?
Headaches
Nausea
Infertility in males
Anaemia
What is the treatment for acute relapse of IBD?
IV hydrocortisone/prednisolone
Immunosuppressants where above does not work (cyclosporin, methotrexate, azothioprine)
What are cytokine modulators?
Tumour necrosis factor inhibitors given as a 12 month course in IBD
Give examples of cytokine modulators.
Infliximab, adalimumab
Define constipation.
Excessive water removal causing less frequent, hard stools
Give examples of causes of constipation.
Diet and lack of fluid
Diverticulae
Paralysis
Drugs- opiates, CCBs
What are bulking agents?
Stimulate peristalsis to reduce constipation
Give examples of bulking agents.
Ispaghula husk
Dietary fibre
What are osmotic laxatives?
Increase water content of the bowel
Give examples of osmotic laxatives.
Lactulose
Macrogol
Give examples of softening agents.
Docusate
Glycerol
What is coeliacs disease?
Autoimmune response to gluten, causing damage to brush border of small intestine and reduced absorption
What are common indications for prescribing ACBS?
Disease related malnutrition Intractable mal absorption Dysphagia Pre-operation preparation Short bowel syndrome/bowel fistula
What is the most common reason for a temporary stoma?
The divert faeces away from surgical site or obstruction
Give some examples of problems that may occur with appliances such as stomas.
Leaking Stoma size changes Skin problems Dexterity Odours
