DRUGS & GIT

Drugs & GIT:

A-Drugs causing Hepatotoxicity:

1. α-methyl dopa(α2-agonist-antiadrenergic-used in treatment of hypertension, is the drug of choice in hypertension during pregnancy).
2. Dantrole (direct skeletal muscle relaxant, ↓Ca release from sarcoplasmic reticulum, life-saving in malignant hyperthermia and neuroleptic malignant syndrome , given I.V).
3. Statins e.g; simvatatin (anti-hyperlipidemics).
4. Fibrates e.g; clofibrate (anti-hyperlipidemic).
5. Toxic doses of paracetamol (or if given with HME inhibitors as alcohol and phenobarbitone) due to accumulation of NABQI.
6. Colchicine (anti-inflammatory in gout).
7. Tolcapone( COMT-inhibitor used in parkinsonism with L-dopa).
8. Phenytoin( anti-epileptic+anti-arrhythmic).
9. Oxazolidinediones( anti-epileptic in petit-mal epilepsy).
10. Sodium Valproate (broad-spectrum antiepileptic).
11. MAO-inhibitors (anti-depressants).
12. Halothane (inhaled general anaesthetic).
13. Tetracyclines( antibiotics).
14. Sulphonamides( anti-bacterial).
15. Isoniazid.
16.
(Anti-T.B)Pyrazinamide.
17. Ethionamide.
18. Para-amino-salicylic acid.

19.
Anti-fungal
Ketoconazole.
20. Griseofulvin.

21. Cis-platin (anti-cancer).

B-Drugs causing Diarrhea:

1-Parasympathomietics: e.g Carbachol – Bethanecol -Neostigmine
(Stimulate M Receptors in Small Intestine)
2-Adrenergic Neurone Depressants : e.gGuanethidine –Reserpine
(They causes Parasympathetic Predominance)
3-Dantrolene which is direct skeletal muscle Relaxant
4- Oral Iron : e.g Ferrous Fermanate & Gluconate ,May cause black or bloody diarrhea
(Some oral iron causes constipation )
5-Magansium Oxide –Hydroxide –Trisilicate :used as Chemical antacids
6-Metoclopramide : Antemitic & Prokinitic
7-Domperidone: Antiemitic & Prokinitic
8-Purgatives (chemical & physical)
9-Colchicine : used in Acute gouty anthritis, may causes bloody diarrhea
10- Erthromycin : Anthmicrobial (Diarrhea is due to prokinietic
11-Broad Spectrum Antimicrobials (especially if not completely absorbed )
e.g Ampicillin –Tetraglclines- Chloramphenicol –Cophalosporins
(Due to Superinfection)
12-PG-Analogues :e.g Misoprostol (see Peptic ulcer)

C-Drugs Causing Constipation:

1-Antimuscarinic Drugs (Anticholinergic Drug =Parasympatholytics)
e.g: Atropine –Hyoscine-Antisecretory –Antispasmodic –Atropine substitutes
2-Opiod Analgesics: e.g Morphine –Mepridine –Loperamide-diphenoxylate (note that lopramide and diphenoxylate are not analgesics) they stimulate opioid receptors in GIT
3-Aluminum Hydroxide Gel :Act as Chemical & physical Antiacid
4-Calcium Carbonate :chemical Antacid
5-Calcium channel blockers :e.g Nifedipine –Veraparmil
6-Drugs Having marked ” Atropie-like Action”;e.g
-1st Generation (=sedating ) Anti-histaminics as Diphenhydramine
-Disopyramide : class I-Anti-arrhythmic
-Tricyclic anti-depressants as imipramin
-Carbamazepine : Anti-epileptic

D-Drugs Causing Nausea &Vomiting:

1-Opioid Analesics :e.g Morphine ,Methadone ,Meperidine
2-Cardiac Glycosides (Digitalis ) :e.g Digoxin ,digitoxin
3-Methylxanthin :e.g Aminophylline , Theophyline
4-D2-Agonists :e.g L-Dopa , Bromocriptine
5-Estrogen (oral contraceptive) causes mainly nausea
6-Cancer chemotherapy

E-Drugs causing Allergic Cholestatic Hepatitis :

1. Carbamazepine(anti-epileptic).
2. Tricyclic antidepressants (TCA's).
3. Chlorpromazine (anti-psychatic).
4. Erythromycin (antibiotic).
5. Chlorpromazine (anti-diabetic).
6. Oral contraceptives.
7. Rifanpicin(anti-T.B)
8. H2-blockers as Cimetidine (anti-ulcer).

F-Drugs activated by gastric acidic medium:

1-Chlorazepate (Benzodiazepine: anxiolytic &hypnotic)
2-Proton Pump Inhibitors e.g. Omeprazole (Antisecretory drugs used in treatmentof peptic ulcer)
3-Sucralfate (mucosal protective agent, used to prevent recurence)
N.B.:
Ketoconazole (Antifungal) absorption increases in acidic medium

G-Drugs destroyed by gastric acid:

1-Acid-sensitive penicillins(e.g. benzyl penicillinG, procaine penicillin , benzathine penicillin , methicillin , cabencillin , ureido-penicillins)
2- Erythromycin (to protect against HCL, erythromycin is given as enteric-coated tablets, or estolate ester is added to erythromycin)

H-Drugs destroyed by proteolytic enzymes: (Not effective orally)

1- Polypeptide antibiotics: Bacitracin & Polymixins
2- Polypeptide hormones: e.g. Insulin, Growth hormone, Glucagon, ACTH, ADH (vasopressin)