constipation drugs Flashcards
name 4 bulk forming laxatives
○ Bran
○ Ispaghula husk
○ Methylcellulose
○ Sterculia
- MOA for bulk forming
○ Relieve constipation by increasing faecal mass which stimulates peristalsis
How to remember treatment of constipation and in pregnancy - BOSS
bulk
add or switch to osmotic if still hard stools
if soft stools but difficult to pass, stimulant
can also add stool softener e.g. docusate
why is it important to drink enough fluids and avoid taking it immediately before bed - bulk forming
can cause intestinal obstruction
how long does lactulose take
48h
which osmotic to offer first - macrogol or lactulose
macrogol
onset of action glycerol suppositories
15-30mins
name the stimulant laxatives: BSSCC
bisacodyl
Senna
sodium picosulfate
co danthrumer
co danthrusate
what colour does Senna colour urine
red brown
which bulk forming laxative has stool softening properties
methylcellulose
onset of action for stimulant laxatives
6-12hours
onset of action for Senna
8 hours - overnight
name 3 osmotic laxatives
Macrogols
Lactulose
Magnesium hydroxide (traditional remedy, less commonly used)
SE lactulose name 4
Flatulence
Abdomial crams
Nausea
Bloating - avoid in IBS! Can make symptoms worse
can be troublesome in the first few days but it does settle
other stimulants (not BSSCC)
glycerol (lubricant and rectal stimulant)
docusate (softener and weak stimulant)
MHRA - new pack size restrictions for stimulant laxatives OTC - B,S,S
should only be used for short term occasional constipation if dietary and lifestyle measure and bulk and osmotic ineffective
GSL: adults only! 18+
limited to pack size of 2 short treatment courses.
max pack size: 20 tabs or 100ml liquid
true or false - Senna can only be bought OTC for adults
false
GSL is 18+ only
but P: 12-17 year olds under advice of pharmacist
under 12 - prescriber !!
prolonged or excessive use can cause…
hypokalaemia
avoid this near term or in history of unstable pregnancy
Senna, other stimulants - they can stimulate uterine contractions
how many tablets are you allowed to buy for Senna GSL
1 pack of 20 tablets
max strength tabs: 1 pack of 10
how many tabs of Senna can you buy (P med) for children and adults 12+
up to 100 under pharmacist supervision
minimum ml of water to take ispahgula husk with
150ml
pt and carer advice isphagula husk - when to take
Preps that swell in contact with liquid should always be carefully swallowed with water and should not be taken immediately before going to bed
how long does fybogel take to work
2-3 days
how do osmotic laxatives work
increase the amount of water in large bowel either by drawing fluid from the body into bowel or by retaining the fluid they were administered with
how long does macrogol take to work
1-2 days
is lactulose absorbed from the GIT
no
is lactulose ok in pregnancy
yes
how do stimulants work
increase intestinal motility/peristalsis and often cause abdominal cramp
how long do bisacodyl tabs take to work
10-20 hours
how long do bisacodyl suppositories take to work
20-60 mins
onset of action of sodium picosulfate
6-12 hours
how do faecal softeners e.g. docusate and glycerol and arachnis oil enemas and liquid paraffin work
Claimed to act by decreasing surface tension and increasing penetration of intestinal fluid into faecal meds
Liquid paraffin has also been used as a lubricant for the passage of stools but manufacturer advised that it should be used with caution because of its adverse effects e.g.
(3)
Anal seepage
Risks granulomatous disease of GIT
Lipoid pneumonia on aspiration
how do enemas containing arachis oil (ground nut oil, peanut oil)
lubricate and soften impacted faeces and promote a bowel movement
how long does oral docusate take to work
1-2 days
how long does rectal docusate take to work
within 20 mins
advice about taking glycerol suppositories
Moisten suppositories with water before insertion
what to use 1st line in opioid induced constipation (+ an alternative, not the opioid receptor antagonists)
Lactulose and Senna
The osmotic laxative will draw water and soften hard stores
The stimulant laxative increases peristalsis which counteracts the anti motility effects of opioids
Alternative: docusate which is a stimulant with stool softening properties
name 2 opioid receptor antagonists that are licensed for opioid induced constipation when other laxatives fail
and how do they work
Methylnaltrexone
Naloxegol
They are peripherally acting opioid receptor antagonists and block the constipating effects of opioids without causing central effects
What is the carcinogen in co-danthrumer and co danthusate
Danton
why should you avoid Bisacodyl and Senna at term or if Hx unstable pregnancy
they can simulate uterine contractions
how much ml to add to macrogol and ispahgula husk
M = 100
IH = 150
