Pharmacology Review Review Sheets: Sheets: GI Drugs, p.1 Stimulants of GI secretion Drug Dru g
Class Cl ass Mechs Mec hs of Actio Act ion n Pharmacokinetics/Adverse Pharmacokinetics/Adverse Effects/Other Effects/Other Comments ∗ Inhibits phosphodiesterase ↑ cAMP ↑ acid production Caffeine Found in coffee, cola, several OTC drugs (ask about this)
∗ Ganglionic stimulation of vagus
Nicotine
∗
↑ acid, ↑ pepsin
∗ ↑ gastrin ↑ gastrin release; ↓ mucus production and dilutes mucus Alcohol (higher conc’s) Cortic Corticost osteroi eroids ds Anti-i Anti-infl nflamm ammato atory ry ∗ Inhibits prostaglandin synthesis Sali Salicy cylat lates es (aspiri (aspirin) n) Anti Anti-i -inf nflam lammat mator ory y ∗ Direct keratolytic effect on epithelium ∗ Old aspirin can clump together, ↑ the damage done NSAIDs
Anti-inflammatory
∗ Inhibits cyclooxygenase (COX) and thus prostaglandin synthesis
Treatment of peptic peptic ulcers Class Cla ss
Drugs Drug s in that Class Cla ss Mechs of Action Acti on Pharmacokinetics/Adverse Pharmacokinetics/Adverse Effects/Other Effects/Other Comments Tranquilizers ∗ ↓ cephalic phase stimuli (used mostly for stress) Sedatives ∗ Muscarinic ACh blocker AnticholinergicsAtropine class isn’t that important b/c of side effects Pirenzipine ∗ Specific M1-Muscarinic ACh blocker
H-2 blockers Cimetidine Ranitidine
∗ H2-histamine receptor blocker
∗ This
Famotidine Pros Prosta tagl glan andi din n Miso Misopr pros osto toll (PGE (PGE1 analog) ∗ Inhibits adenyl cyclase, ↓ cAMP analogs Pro Proton ton pum pump p Omep Omepra razo zole le (Pri (Prilo lose secc®) ∗ Highly specific and irreversible inhibitor of H +-K +-ATPase (↓ gastric acid secretion) inhibitors ∗ Specialized to work in acid environments ONLY (i.e. the stomach) (PPIs) Lansoprazole (Same as omeprazole) action: Longer-acting than omeprazole
∗ Duration of ∗ Adverse effects: Fewer than
omeprazole Mucosal protectan tants
Bismuth su subsalicylate ∗ Coats lining of stomach ∗ Suppresses H. pylori (Pep (Peptto-Bismo smol®)
Sucrulfate
∗ Binds necrotic tissue (once there’s damage) to prevent further erosion
Antacids Sodium bicarbonate effects: If pH is raised to > 4, (systemic)
∗ Neutralizes acid
∗ Adverse - ↓ Pepsin activity - Release of CO2 (perforation
risk) - Metabolic alkalosis ∗ Otherwise, nice b/c it’s really really really cheap! Antacids Laxative: Mg ox oxide Adverse effects: (nonsystemic) Mg hydroxide entire drug class
∗ Neutralizes acid
∗ - Laxative, for the
Mg trisilicate to slight absorption Constip.: Al3+ salts
- Central depressants due
∗ Neutralizes acid
∗ Adverse
effects: Al hydroxide gel other antibiotics (bad for patient
- Binds tetracycline, (being treated for H. pylori) - Al3+ poisoning
Calcium salts ∗ Neutralizes acid ∗ Adverse effect: Possible urinary urinary calculi (stones) Note: Current treatment: COMBO therapy Present CDC recommendation: Lansoprazole, Amoxicillin initially, then follow follow up with H2-blockers H2-blockers and proton pump inhibitors for 6 months months FDA recommendation (12/95): Clarithromycin, omeprazole and ranitidine, bismuth citrate initially, then follow up with H2-blockers and proton pump inhibitors for 6 months NIH recommendation (2/94): Amoxicillin or tetracycline, metronidazole, bismuth subsalicylate initially, then follow up with H2-blockers and proton pump inhibitors for 6 months
Pharmacology Review Review Sheets: Sheets: GI Drugs, p.2 Antidiarrheal agents Class Cla ss
Drugs Drug s in that Class Cla ss Mechs of Action Acti on Pharmacokinetics/Adverse Pharmacokinetics/Adverse Effects/Other Effects/Other Comments Abso Absorb rben ents ts Kaop Kaopec ecta tate te:: Kaol Kaolin in (hyd (hydra rate ted d sili silica cate te clay clay)) available; inexpensive
∗ Widely
combined with pectin (from fruit) ∗ Adverse effects: Relatively safe, but may interfere with absorption ∗ RadioBismuth subsalicylate (Pepto-Bismol®) Binds intestinal toxins opaque: stop using before GI series Coats internal lining of stomach ∗ Adverse effect: Innocuous tarry (black) discoloration of stools ∗ Powerful, reliable inhibitor of GI motility Opiates Diphenoxylate (Lomotil® w/atropine) ∗ Contraindication: Children < 2 years of age - ↑ GI tone, but ↓ peristalsis ∗ Often used for traveler’s diarrhea Loperamide (Immodium ®) ∗ Inhibits peristaltic reflux ∗ Structure: Chemically similar to haloperidol and meripidine ∗ ↓ PG-mediated contraction ∗ Duration of action: Longer than diphenoxylate ∗ Side effect: Abdominal pain ∗ Best anti-diarrheal agent currently Codeine
∗ ↑ GI tone
∗ Adverse effect:
Addictive
Paregoric (camphorated opium tincture)
∗ ↓ Peristalsis
Laxatives
elimination of poisons, combo with Indications: Hemorrhoids, stool softeners (before an X-ray), elimination antihelminthics (to finish the job), for a better stool sample. NOT to get a daily bowel movement!
Class Cla ss
Drugs Drug s in that Class Cla ss Mechs of Action Acti on Pharmacokinetics/Adverse Pharmacokinetics/Adverse Effects/Other Effects/Other Comments ∗ Retain water in lumen Osmotics Saline cathartics: Mg citrate, Mg oxide Hydrophilic colloids: colloids: Agar, methyl cellulose, bran, prunes Irritants Esmodin ∗ Adverse effects: Eventual dependence for bowel movement (Largest gr group; Castor oi oil usually usually too too potent) potent) Phenolphth Phenolphthalein alein (Ex-Lax (Ex-Lax ®)
∗ Admin/duration of action: Oral
Bisacodyl: (6 hrs), rectal (15-60 min)
∗ Adverse effects: Lacks significant side-effects
∗ Can be used in any patient!! Lubricants
∗ Adverse effects: - Dangerous foreign-body reaction in
Mineral oil
some people - Inhibits absorption of essential fatsoluble vitamins (A, D, E, K) - Leaks through the anal sphincter (can’t be used for a long time) Docusate
Emetics
∗ Stool softener
∗ Duration of action: Slow ∗ Adverse effects: Safe
Indications Indication s
Contraindications Contraind ications
∗ Ridding the stomach of noxious substances ∗ Lacerations, rupture of stomach/esophagus ∗ First aid treatment of poisoning (Ipecac used here) ∗ Fluid and electrolyte imbalance ∗ Used w/certain anti-helminthic treatments ∗ Interference w/successful outcomes of surgery ∗ Ingestion of strong acids/alkalis, b/c you’ll do more damage as it comes back up. Treat by neutralizing acid or base. ∗ Ingestion of kerosene, petroleum distillates b/c it has an anaesthetic effect in the lungs, and sensitizes cardiac activity to catecholamines. Can result in foreign body reaction with lymph. Note that insecticides/pesticides may be packaged w/kerosene and petroleum distillates ∗ Strychinine (rat poison) poisoning b/c you may set off convulsions w/excitation of the vomiting center. Put them in room w/low light levels, ↓ stimuli, then treat ∗ Unconscious patient (b/c of possible lung damage) Drug
Pharmacokinetics/A Pharmacoki netics/Actions/Mech ctions/Mechss of Action Adverse Effects Syrup of of ipecac Admin/Dose: Admin/Dose: Oral; 15 mL (½ oz.)repeat oz.)repeated ed at 20-30 mins mins if necessary; necessary; stop if it doesn’t doesn’t work ∗ Don’t give w/activated charcoal b/c it’s a good absorber after 3 administrations Mechanism of action: Acts by irritating stomach, stomach, possibly by releasing serotonin (5-HT) ∗ Doesn’t always work!! Apomorphin Apomorphinee Administrati Administration/Do on/Dose: se: Subcutaneou Subcutaneous; s; 2 mg should should induce induce vomiting vomiting in 5-10 minutes minutes ∗ No amnesia, drowsiness Mechanism of action: Stimulates chemoreceptor trigger zone (CTZ) ∗ Almost always works Pharmacology Review Review Sheets: Sheets: GI Drugs, p.3
Anti-Emetics Class Cla ss
Drugs Drug s Pharmaco Phar macokine kinetics tics/Act /Action ions/Mec s/Mechs hs of Action Acti on Uses Adverse Effects Anti Antich chol olin iner ergi gicsScop csScopol olam amin inee Admi Admin: n: Subc Subcut utan aneo eous us patch, poss. given w/dextramphetamine or ephedrine ∗ Motion sickness ∗ Can, but shouldn’t be used in pregnancy ∗ Duration of action: SHORT Anticholinergic side-effects Anti Antihi hista stami mine ness Bucli Buclizi zine ne ∗ Teratogenic potential: phocomelia (short/absent limbs) Cyclizine - Seen w/ buclizine, cyclizine, meclazine, hydroxyzine ∗ Drowsiness Meclizine ∗ Anti-cholinergic sideHydroxyzine effects ∗ Can, but shouldn’t be Dimenhydrinate OTC used in pregnancy Benadryl OTC ∗ Action: Works at chemoreceptor trigger zone (CTZ) Anti Anti-d -dop opam amin iner ergi gics cs Chlo Chlorp rpro roma mazin zines es ∗ Rx of vomiting and nausea ∗ Parkinson-like side effects Prochlorperazine assoc. w/toxins, radiation ∗ Drowsiness Perphenazine sickness, cytotoxic drugs ∗ Orthostatic hypotension ∗ Anti-cholinergic sideTriethylperazine effects (xerostomia, etc.) ∗ Cholestatic jaundice
∗ Granulocytopenia, leukopenia, thrombocytopenia RARE ∗↓ Metoclopromide ∗ Admin: Give ALONE (NOT w/anticholinergics, antihistamines) incidence of GI reflux ∗ Drug Interactions: ergotamine, sedatives, analgesics ∗ Actions: Works at CTZ; stimulates stimulates GI ↑ LES pressure (used in migraines) ∗ Sedation, Parkinson-like effects 5-HT3 ant antagonists Grani anisetr etron ∗ Used in cancer Odansetron chemotherapy Misce Miscell llan aneo eous us Prom Promet etha hazin zinee Mech Mechan anis isms ms of acti action: on: Weakl Weakly y anti anti-do -dopa pami mine nerg rgic, ic, weak weakly ly ∗ Parkinson-like side effects from antidopaminergic properties anti-histaminic, weakly anti-cholinergic. Can act at CTZ ∗ Used for post-op nausea ∗ Benzquinamid Benzquinamidee Admin: Admin: Administer Administer slowly slowly Avoid in patients with hypertension, severe CV disease Effects: Anticholinergic, antihistaminic, antidopaminergic, mild sedative ∗ Don’t use in pregnancy Duration of of action: Short (t½ = 40 min) Dipheni enidol Effect ects: Cent entral anticholin linergic; acts cts on vestibular apparatus and CTZ ∗ ∗ Visual/auditory hallucinations, disorientation, confusion Toxin-assoc. nausea/vomiting ∗ Radiation sickness ∗ Anticholinergic side-effects ∗ Postoperative ∗ Pregnancy concerns ∗ Following general anesthesia Trimet Trimethob hobenz enzamid amidee Effects Effects:: Not as effect effective ive as as antid antidopa opamin minerg ergics ics ∗ ↓ incidence of adverse reactions (drowsiness, Parkinson-like
syndrome, orthostatic hypotension
∗ Don’t’ give to children w/acute febrile illness, gastroenteritis, encephalitis, electrolyte imbalances (b/c of Reye’s synd. risk) Dronabinol Schedule II Drug : Limit it to a necessary amount
∗ Used to treat nausea
in pts. (∆9-tetrahydro-
Absorption: Poor (10-20%)
in chemotherapy, or in
which canna cannabi bino nol) l) Metab Metabol olism ism:: Exte Extens nsiv ivee 1st pass metabolism other antiemetics have failed Elimination: Biphasic elimination (fast for 4 hrs, slow for 25-36 hrs) ∗ Same as dronabinol Nabilone Schedule II Drug : Limit it to a necessary amount Admin/Action: Oral; peak in 2 hrs Emet Emetro roll Adm Admin: in: Oral Oral soln soln of dextr extros ose, e, lev levulos ulose, e, phos phosph phor oric ic acid acid,, lem lemon on/m /min intt fla flav vor ∗ Don’t use in people with fructose intolerance Effect: Acts on wall of GI tract to ↓ smooth muscle contraction, for “relief of upset stomach” ∗ Has Bi subsalicylate subsalicylate Effect: Coats stomach to ↓ irritation salicylate; don’t use in people w/aspirin intolerance (Pepto-Bismol®)
