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YFRM 300 > Drugs used in disorders of the bowel > Flashcards

Drugs used in disorders of the bowel Flashcards

1
Q
  • Nausea
A
  • Nausea is an unpleasant sensation,
    which may be a precursor to the forceful
    expulsion of gastric contents
    (vomiting/emesis
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2
Q

Vomiting centre

A

The physical act of vomiting is co-ordinated centrally by the vomiting (or emetic) centre in the medulla

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3
Q
  • A network of neural pathways that integrate signals arriving directly from other locations such as:
A

the inner ear through the vestibular nuclei (which explains the mechanism of motion and Meniere’s disease) * It receives input from higher cortical centres, explaining why unpleasant or repulsive sights or smells, or strong emotional stimuli, can sometimes induce nausea and vomiting. (emotional, visual, olfactory impulses)

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4
Q

Chemoreceptor trigger zone (CTZ)

A

found In the postrema of the medulla
protected by Blood brain barrier-Lipophilic drugs

It is rich in D2, 5HT and neurokinin receptors. The neurotransmitters
at these receptors are dopamine, serotonin and subst P respectively.

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5
Q

Opioid receptors are also found in the CTZ. why?

A

because opioids cause Nausea and vomit

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6
Q

Presence of abdominal pain

A

N&V as a symptom of appendicitis, cholecystitis (inflammation of gallbladder) & cholelithiasis
(presence of formation of gallstones) – abdominal pain would be the presenting symptom.

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7
Q

Timing of nausea and
vomiting

A

Early morning vomiting = ?Pregnancy / excess alcohol intake
Immediately after food = ?gastritis
1 or more hours after food = ?peptic ulcer

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8
Q

Conditions to eliminate

A
  • N&V associated with headaches (migraines / raised intracranial
    pressure) * N&V in neonates (birth to 1 month) = ALWAYS referred
  • N&V (differentiate from regurgitation) in infants (1 – 12 months) -
    refer in 24 hours
  • N&V in children – rehydration! * Medicine-induced
  • Middle ear diseases
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9
Q

D2 receptor antagonists

A
  • Not for vomiting because of motion sickness/labyrinth disturbances
  • Hydrophilic drugs preferred- will not cross BBB
  • Will not block extrapyramidal D2 receptors: dyskinesia & restlessness
    Dopamine inhibits prolactin, its blockage may cause breast tenderness,
    galactorrhoea, amenorrhea.
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10
Q

D2 receptor antagonists: crossses BBB

A

Metoclopramide

postoperative vomiting
drug related N/V
empties stomach and relaxes pylorus

Prochlorperazine:

radiation therapy, oncotherapy, available as
suppositories.
* AE: jaundice

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11
Q

Histamine & Muscarinic receptor antagonist

A

Used for all types of vomiting esp motion sickness, nausea from
labyrinth disturbances
Cross BBB = vomiting centre & chemoreceptor trigger zone (CTZ)
Anticholinergic side-effects

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12
Q

drugs

A

Promethazine – sedative anithistamine – treat motion sickness &
vertigo AE: Strong anticholinergic effect ,Strong sedative effect
Cyclizine – also paediatric suppositories for over 6 years – treat motion
sickness
Cinnarizine - treat motion sickness, vertigo, vestibular disorder

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13
Q

5-HT3 antagonist

A

Examples: * Dolasetron
* Granisetron
* Ondansetron
* Palonosetron

Selective antagonists of 5HT receptors in chemoreceptor trigger zone
(CTZ) & GIT
* N/V caused by chemotherapeutic drugs, radiation therapy
* Caution in cardiac disease- ECG abnormalities

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14
Q

Pregnancy

A

Management * Reassurance
* Attention to emotional factors
* Cup of tea with a biscuit before rising
* Light frequent meals with adequate fibre intake
* Mixture of sucrose & phosphoric acid (Emetrol® or Emex®) * Drug treatment not recommended – moderate N&V
* Doxylamine (Somnil®, Restwell®) most evidence in pregnancy
* Combination preparation: S2 Asic® doxylamine + dicyclomine + pyridoxine:
2t nocte, 1t mane before rising prn

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15
Q

severe type of vomiting during pregnanc

A

Hyperemesis gravidarum (severe type of vomiting during pregnancy) * Admission to hospital * IV hydration with electrolytes and thiamine
* Parenteral antiemetics: * IM prochlorperazine
* IV metoclopramide
* Ondansetron for pregnancies over 12 weeks if vomiting does not resolve
* Exclude organic causes: thyrotoxicosis, UTI, gestational trophoblastic
diseas

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15
Q

Neurokinin 1 receptor antagonists

A

Aprepitant
Adjunct to other antiemetics for prevention of acute or delayed N&V
due to highly emetogenic chemotherapy

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16
Q

Irritable bowel syndrome (IBS)

A

A functional bowel disorder of the GIT associated with: * Abdominal pain and * Altered bowel activity * Lacking any pathological changes.
Synonyms: spastic colon, irritable colon

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17
Q

Irritable bowel syndrome: sub-classification

A
  • IBS-D: IBS with predominant diarrhoea
  • IBS-C: IBS with predominant constipation
  • IBS-M: IBS with alternating constipation & diarrhoea
18
Q

Irritable bowel syndrome: aetiology

A

Multifactorial cause (not sure) * Motility dysfunction
* Diet * Genetics * Psychological factors (stress /
depression

19
Q

Antispasmodics

A

(Antimuscarinic / anticholinergic) * Dicycloverine
* Mebeverine
* Propantheline
* Hyosine*
! Reduce GI motility

20
Q

Motility stimulants (propulsives):

A

mainly IBS-C
enhance gastric emptying,
decrease small bowel transit time
& increase gastro-oesophageal
sphincter tone
Role in IBS not defined
* Metoclopramide
* Domperidone

21
Q

Propulsives

A

Domperidone
* Peripheral dopamine blocking
agent * DI: metabolised via cytochrome
P450 in liver, QT prolongation
* DI: grapefruit juice

Metoclopramide
* IBS: Off label use
* SE: CNS; drowsiness, fatigue,
dizziness, weakness, abdominal
cramps & diarrhoea !!
Extrapyrimidal effects in elderly
and children
* DI: antipsychotics, CNS
depressants, alcoho

22
Q

Inflammatory bowel disease

A

A chronic inflammatory disorder of the
gastrointestinal tract that includes both
Crohn’s disease (CD) and ulcerative
colitis.

23
Q

symptoms for both

A

: Abdominal pain, rectal bleeding,
diarrhoea and weight loss characterise
both CD and ulcerative colitis.

24
Q

Sulfasalazine

A

Split by colonic bacteria into sulfapyridine and 5-aminosalicylic acid (5-
ASA, mesalazine). 5-ASA believed to be responsible for beneficial
effect.
* Sulfapyridine absorbed, metabolised in the liver and excreted via the
urine.
* Most of 5-ASA eliminated unchanged in the faeces

25
Q

Contraindications:

A

Prescriber’s points: * Monitor blood counts, hepatic function, urea and electrolytes with chronic
therapy
* GI adverse effects can be alleviated by a drug holiday and starting at a lower dose
* Gastric irritation may be minimised by taking after meals, full glass of water,
enteric coated tablets
* Report sore throat, fever or easy bruising – indicated heamotologic abnormalities
(thrombocytopenia, granulocytopenia, red cell haemolysis

26
Q

Relapses of Crohn’s disease

A

Immunosuppressants e.g. azathioprine, mercaptopurine, methotrexate
PLUS (if necessary)
Tumour necrosis factor – α inhibitors (TNF-α inhibitors) e.g. infliximab,
adalimumab

27
Q

Constipation

A

A reduction in normal bowel habit accompanied with more difficult
defecation and/or hard stools

28
Q

what causes constipation

A

Very common, especially in the elderly
Causes: sedentary lifestyle, ↓ fluid intake, poor nutriƟon, avoidance of
fibrous foods, chronic illness, pregnancy, drugs, chronic use of enemas
& laxatives, old age, ignoring the urge
Women more likely than men
Late pregnancy (40%)

29
Q

Normal function of large intestine

A

Normal function of large intestine =
remove water and various salts from
colon, drying and expulsion of faeces

30
Q

increase in absorption will lead to ??

A

Constipation.

31
Q

Pain on defecation

A

Anorectal problem; constipation usually secondary to the suppression of
Anorectal problem; constipation is usually secondary to the suppression of
defecation, because it induces pain

32
Q

Presence of blood

A

Bright red = haemorrhoids / tear in anal canal
Blood mixed with stool = refer
Stool appear black and tarry = upper GI bleed

33
Q

chronic constipation duration

A

duration >/= 6 weeks

34
Q

Constipation: conditions to eliminate

A

Medicine-induced constipation
IBS
Pregnancy
Functional causes in children
Depression
Colorectal cancer
Hypothyroidism
Bowel obstruction

35
Q

Non-pharmacological measures

A

Dietary:↑ fibre & water intake – 3-5 days
Avoid caffeinated drinks and diuretics
Lifestyle: ↑ exercise
Encourage regular bowel habits
Discourage continuous use of laxatives

36
Q

Class of laxative

A

Bulk-forming-Softening and increasing feacal
mass, increased bulk
encourage peristalsis
(mimic ↑ fibre consumpƟon)

drugs
Ispagula* (psyllium) (Agiobulk®, Fybogel®) * Methylcellulose * Sterulia (Normacol®)

Contact/irritant–↑ GI moƟlity by directly
stimulating colonic nerves

Senna* (Senokot®, Soflax®)
* Sodium picosulphate (metabolised by colonic
bacteria to active metabolite bisacodyl) * Bisacodyl (Dulcolax® supps & enteric coated).

Osmotically acting—Withdraw fluid into the bowel
by osmosis

drugs
Lactulose*
* Magnesium sulphate / hydroxide
* Polyethylene glycol combinations* (Movicol®,
Go-lytely®, Klean-Prep®) * Sodium phosphate* (Colo-pre

37
Q

Bulk-forming laxatives

A

Non-habit-forming, supplements to dietary fibre
* Indications: constipation, IBS, diverticular disease
* Onset of action: 12-72 hours
* Contraindications: intestinal obstruction, stenosis, ulceration or adhesions
in the GIT
* Caution: sodium-containing product, increase fluid intake to avoid intestinal compaction
* Pregnancy √ (safe) * Drug interactions: may interfere with absorption of certain drugs (take 3 hours before or after other drugs) * Adverse effects: flatulence & abdominal distension.

38
Q

Contact / irritant laxatives

A

ndications – can precipitate chronic colonic changes
* Onset of action: 8-12 hours
* Pregnancy – avoid
* ! Abuse as slimming aid
* Adverse effect: abdominal cramps, long term use
Bisacodyl and Sodium picosulphate
* Indicated for single dose administration to evacuate bowel in preparation
for examinations of the colon (including radiological examinations) or to
evacuate barium from the GIT after radiological examination

39
Q

Osmotically acting laxative

A

Onset of action: 12-72 hours
* Generally used for acute and rapid evacuation of the bowel (except
lactulose), prolonged use not recommended
* Indications: bowel preparation for colonoscopy / colon surgery /
radiological examination should receive split dose preparations,
significantly improve bowel cleansing. Administer half the evening
before the procedure and the other half on the morning (4-6 hours)
before the procedure
* Polyethylene glycol combinations include Go-Lytely® and Klean-Prep®
* Sodium phosphate include Colo-Prep®

40
Q

Rectal laxative preparations

A
  • Suppositories
  • Bisacodyl, * Glycerol (osmotic effect softens and lubricates faeces, mildly irritant effect
    causing rectal contraction, evacuation usually within 30 minutes) * Enemas
  • Sodium phosphate
41
Q

Haemorrhoids

A

Most common problem affecting the anorectal
region
Varicose veins of the ano-rectal area.
Is usually accompanied by a history of
constipation.
In older patients consider a diagnosis of underlying carcinoma.
GENERAL MEASURES
High-fibre diet.
Counsel against chronic use of laxatives.
Avoid straining at stool

42
Q

Symptomatic treatment for painful haemorrhoids:

A

Bismuth subgallate compound, ointment, topical, applied 2–4 times
daily
OR
Bismuth subgallate compound suppositories, insert one into the
rectum 3 times daily.
OR
Lidocaine 2%, cream, topical, applied before and after each bowel
action.

43
Q

Anal fissures

A

Painful small cracks just inside the anal
margin, sometimes a linear ulcer.
It is often seen together with a
sentinel pile or external
haemorrhoids.
May cause spasm of the anal
sphincter.
May cause bleeding on defecation.
Dietary advice – promote soft stools

YFRM 300 (18 decks)

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