[DISPENSING] Therapeutic Incompatibilities & Drug Interactions Part 2

• Amoxicillin

• Acetazolamide

• Aspirin

• Chlorothiazide

• Ciprofloxacin

• Cephalexin

• Ethacrynic Acid

• Furosemide

• Ibuprofen

• Levodopa

• Methotrexate

• Phenytoin

• PTU (Propylthiouracil)

• Salicylic acid

• Sulfadiazine

• Sulfapyridine

• Theophylline

• Tolbutamide

• Warfarin

• Methyldopa (Both weakly acidic / basic due to its amphoteric nature)

• Penicillamine

• Pentobarbital

• Phenobarbital

[ALTERATION OF PH]

Example of Weakly acidic drugs

• Alprenolol

• Allopurinol

• Amphetamine

• Atropine

• Chlorpheniramine

• Cocaine

• Diazepam

• Diphenhydramine

• Ephedrine

• Epinephrine

• Imipramine

• Lidocaine

• Methadone

• Methamphetamine

• Methyldopa (Both weakly acidic / basic due to its amphoteric nature)

• Metoprolol

• Morphine

• Nicotine

• Norepinephrine

• Pilocarpine

• Pseudoephedrine

[ALTERATION OF PH]

Example of Weakly basic drugs

a. Acid

[ALTERATION OF PH]

↓ pKa

a. Acid

b. Base

b. Base

[ALTERATION OF PH]

↑ pKa

a. Acid

b. Base

a. Protonated

[ALTERATION OF PH]

pH < pKa

a. Protonated

b. Deprotonated

b. Deprotonated

[ALTERATION OF PH]

pH > pKa

a. Protonated

b. Deprotonated

• Acid becomes unionized

• Base becomes ionized

[ALTERATION OF PH]

pH < pKa = Protonated. Which statement is correct?

a. Acid becomes unionized, base becomes ionized
b. Acid becomes ionized, base becomes unionized
c. Both become ionized
d. Both become unionized

• Acid becomes ionized

• Base becomes unionized

[ALTERATION OF PH]

pH > pKa = Deprotonated. Which statement is correct?

a. Acid becomes unionized, base becomes ionized
b. Acid becomes ionized, base becomes unionized
c. Both become ionized
d. Both become unionized

a. Acidic environment (Lower pH)

[ALTERATION OF PH]

Acidic drugs are more absorbed in an _______ environment

a. Acidic environment (Lower pH)

b. Basic environment (High pH)

b. Basic environment (High pH)

[ALTERATION OF PH]

Basic drugs are more absorbed in a ________ environment

a. Acidic environment (Lower pH)

b. Basic environment (High pH)

a. ↓ pH

[ALTERATION OF PH]

Intake of acidic food

a. ↓ pH

b. ↑ pH

b. ↑ pH

[ALTERATION OF PH]

Intake of alkaline food

a. ↓ pH

b. ↑ pH

b. Administer antacids 2 hours after ketoconazole

[ALTERATION OF PH]

The remedy for Ketoconazole + Antacids interaction is:

a. Administer antacids 2 hours before ketoconazole
b. Administer antacids 2 hours after ketoconazole
c. Administer both together
d. Avoid ketoconazole completely

b. Should not be given within an hour of antacid therapy / ingestion of milk

[ALTERATION OF PH]

The remedy for Bisacodyl + Antacids/milk interaction is:

a. Administer together with food
b. Should not be given within an hour of antacid therapy / ingestion of milk
c. Administer antacids 2 hours after Bisacodyl
d. Increase the dose of Bisacodyl

b. Decreased absorption

[COMPLEXATION / ADSORPTION]

Tetracycline/Quinolones + multivalent cations results in _______

a. Increased absorption

b. Decreased absorption

b. Decreased absorption

[COMPLEXATION / ADSORPTION]

Cholestyramine and Colestipol + fat-soluble drugs (thyroid hormones, digoxin, warfarin, leflunomide, thiazide diuretics, vitamins ADEK) result in adsorption of drugs to the bile acid sequestrant, leading to _______

a. Increased absorption

b. Decreased absorption

b. Bile acid sequestrant

[COMPLEXATION / ADSORPTION]

Cholestyramine and Colestipol + fat-soluble drugs (thyroid hormones, digoxin, warfarin, leflunomide, thiazide diuretics, vitamins ADEK) result in adsorption of drugs to the ______ , leading to decreased absorption

a. Antacid

b. Bile acid sequestrant

c. Proton pump inhibitor

d. H2 blockers

• Thyroid hormones

• Digoxin

• Warfarin

• Leflunomide

• Thiazide diuretics

• Vit ADEK

[COMPLEXATION / ADSORPTION]

Example of Fat soluble drugs [6]

b. Bile acid sequestrants

[COMPLEXATION / ADSORPTION]

Cholestyramine and Colestipol are classified as:

a. Antacids

b. Bile acid sequestrants

c. Proton pump inhibitors

d. H2 blockers

b. Decreased absorption

[COMPLEXATION / ADSORPTION]

Penicillamine + metal-rich foods results in _____

a. Increased absorption

b. Decreased absorption

a. Laxative

[ALTERATION OF GI MOTILITY]

_______ decreases bioavailability of slowly absorbed drugs.

a. Laxative
b. Anticholinergic

a. Stimulant / Irritant

[TYPES OF LAXATIVES]

Bisacodyl

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

a. Stimulant / Irritant

[TYPES OF LAXATIVES]

Senna

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

a. Stimulant / Irritant

[TYPES OF LAXATIVES]

Castor oil

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

b. Bulk-forming

[TYPES OF LAXATIVES]

Psyllium

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

c. Surfactant / Stool softener

[TYPES OF LAXATIVES]

Docusate

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

c. Surfactant / Stool softener

[TYPES OF LAXATIVES]

Polyethylene glycol (PEG)

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

d. Osmotic / Saline

[TYPES OF LAXATIVES]

Na Phosphate (Fleet Enema)

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

d. Osmotic / Saline

[TYPES OF LAXATIVES]

Lactulose

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

d. Osmotic / Saline

[TYPES OF LAXATIVES]

Epsom Salt (MgSO4)

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

e. Lubricant

[TYPES OF LAXATIVES]

Mineral oil

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

e. Lubricant

[TYPES OF LAXATIVES]

Glycerin

a. Stimulant / Irritant

b. Bulk-forming

c. Surfactant / Stool softener

d. Osmotic / Saline

e. Lubricant

b. Anticholinergic

[ALTERATION OF GI MOTILITY]

_______ drecreases motility

a. Laxative
b. Anticholinergic

b. Slow absorption

[ALTERATION OF GI MOTILITY]

Increase GET

a. Fast absorption

b. Slow absorption

a. Fast absorption

[ALTERATION OF GI MOTILITY]

Decrease GET

a. Fast absorption

b. Slow absorption

a. Fast absorption

[ALTERATION OF GI MOTILITY]

Increase GER

a. Fast absorption

b. Slow absorption

b. Slow absorption

[ALTERATION OF GI MOTILITY]

Decrease GER

a. Fast absorption

b. Slow absorption

b. Decrease GER

[ALTERATION OF GI MOTILITY]

Increase GET (Slow Absorption) = _____

a. Increase GER

b. Decrease GER

a. Increase GER

[ALTERATION OF GI MOTILITY]

Decrease GET (Fast absorption) = _____

a. Increase GER

b. Decrease GER

• Stress

• Heavy Exercise

• Antimotility drugs (opioids, anticholinergics)

• Left lying

• Large meal

📌Mnemonic: “SHALL”

[ALTERATION OF GI MOTILITY]

Factors that Increase GET and Decrease GER [5]

• Gastrectomy

• Extremes of food temperature

• Right lying

• Mild exercise

• Spicy foods

• Promotility drugs

• Diabetes mellitus

📌Mnemonic: “GERMSPD”

[ALTERATION OF GI MOTILITY]

Factors that Decrease GET and Increase GER [6]

a. Increase GET

[ALTERATION OF GI MOTILITY]

Stress

a. Increase GET

b. Decrease GET

a. Increase GET

[ALTERATION OF GI MOTILITY]

Heavy exercise

a. Increase GET

b. Decrease GET

a. Increase GET

[ALTERATION OF GI MOTILITY]

Antimotility drugs (opioids, anticholinergics)

a. Increase GET

b. Decrease GET

a. Increase GET

[ALTERATION OF GI MOTILITY]

Opioids

a. Increase GET

b. Decrease GET

a. Increase GET

[ALTERATION OF GI MOTILITY]

Anticholinergics

a. Increase GET

b. Decrease GET

a. Increase GET

[ALTERATION OF GI MOTILITY]

Left lying

a. Increase GET

b. Decrease GET

a. Increase GET

[ALTERATION OF GI MOTILITY]

Large meal

a. Increase GET

b. Decrease GET

b. Decrease GET

[ALTERATION OF GI MOTILITY]

Gastrectomy

a. Increase GET

b. Decrease GET

b. Decrease GET

[ALTERATION OF GI MOTILITY]

Extremes of food temperature

a. Increase GET

b. Decrease GET

b. Decrease GET

[ALTERATION OF GI MOTILITY]

Right lying

a. Increase GET

b. Decrease GET

b. Decrease GET

[ALTERATION OF GI MOTILITY]

Mild exercise

a. Increase GET

b. Decrease GET

b. Decrease GET

[ALTERATION OF GI MOTILITY]

Spicy foods

a. Increase GET

b. Decrease GET

b. Decrease GET

[ALTERATION OF GI MOTILITY]

Promotility drugs

a. Increase GET

b. Decrease GET

b. Decrease GET

[ALTERATION OF GI MOTILITY]

Diabetes mellitus

a. Increase GET

b. Decrease GET

• Bisphosphonates

• Penicillins (except Amoxicillin)

• Penicillamine

• TCN (Tetracyclines)

• Quinolones

• Azithromycin

• Eythromycin stearate

• Captopril

[EFFECT OF FOOD]

Drugs without Food [8]

• Griseofulvin

• Metoprolol

• Phenytoin

• Propoxyphene

• Dicumarol

• Morphine

• Lithium

[EFFECT OF FOOD]

Drugs with Food [7]

b. Drug without food

[EFFECT OF FOOD]

Bisphosphonates

a. Drug with food

b. Drug without food

b. Drug without food

[EFFECT OF FOOD]

Penicillins (except Amoxicillin)

a. Drug with food

b. Drug without food

b. Drug without food

[EFFECT OF FOOD]

Penicillamine

a. Drug with food

b. Drug without food

b. Drug without food

[EFFECT OF FOOD]

TCN (Tetracyclines)

a. Drug with food

b. Drug without food

b. Drug without food

[EFFECT OF FOOD]

Quinolones

a. Drug with food

b. Drug without food

b. Drug without food

[EFFECT OF FOOD]

Azithromycin

a. Drug with food

b. Drug without food

b. Drug without food

[EFFECT OF FOOD]

Erythromycin stearate

a. Drug with food

b. Drug without food

b. Drug without food

[EFFECT OF FOOD]

Captopril

a. Drug with food

b. Drug without food

a. Drug with food

[EFFECT OF FOOD]

Griseofulvin

a. Drug with food

b. Drug without food

a. Drug with food

[EFFECT OF FOOD]

Metoprolol

a. Drug with food

b. Drug without food

a. Drug with food

[EFFECT OF FOOD]

Phenytoin

a. Drug with food

b. Drug without food

a. Drug with food

[EFFECT OF FOOD]

Propoxyphene

a. Drug with food

b. Drug without food

a. Drug with food

[EFFECT OF FOOD]

Dicumarol

a. Drug with food

b. Drug without food

a. Drug with food

[EFFECT OF FOOD]

Morphine

a. Drug with food

b. Drug without food

a. Drug with food

[EFFECT OF FOOD]

Lithium

a. Drug with food

b. Drug without food

b. Decreased absorption by 30-40%

[EFFECT OF FOOD]

Captopril + food → _______

a. Increased absorption by 30-40%

b. Decreased absorption by 30-40%

c. 30-40%

[EFFECT OF FOOD]

Captopril + food will lead to a decreased absorption by ______ %.

a. 10-20%
b. 20-30%
c. 30-40%
d. 40-50%

a. Albumin

[PROTEIN BINDING]

The plasma protein that binds acidic drugs is

a. Albumin

b. Alpha-acid glycoprotein (AAC)

b. Alpha-acid glycoprotein (AAC)

[PROTEIN BINDING]

The plasma protein that binds basic drugs is:

a. Albumin

b. Alpha-acid glycoprotein (AAC)

a. True

[PROTEIN BINDING]

Drug interaction by DISTRIBUTION occur when one drug displaces a protein-bound, increasing free concentration of the displaced drug

a. True

b. False

a. Phenytoin toxicity

[PROTEIN BINDING]

Valproic Acid + Phenytoin-Protein → increased free phenytoin → ______

a. Phenytoin toxicity

b. Valproic Acid toxicity

a. Bleeding

[PROTEIN BINDING]

ASA + Warfarin-protein → Increased warfarin → ______

a. Bleeding

b. Thrombosis

b. Hypoglycemia

[PROTEIN BINDING]

Sulfonamide + Sulfonylurea-protein → _______

a. Hyperglycemia

b. Hypoglycemia

a. Increased MTX toxicity

[PROTEIN BINDING]

MTX + Salicylates → Increased free MTX → _______

a. Increased MTX toxicity

b. Increased Salicylate toxicity

• Amitriptyline

• Chlorpromazine

• Flurazepam

• Phenytoin

• Cloxacillin

• Naproxen

• Propranolol

• Lidocaine

• Lorazepam

• Warfarin

• Phenylbutazone

• Penicillin

[PROTEIN BINDING]

Drugs that are >90% Protein Bound [12]

• Aspirin

• Valproic acid

• Salicylic acid

[PROTEIN BINDING]

Drugs that have the highest affinity for plasma proteins and can displace other protein-bound drugs include ________ [3]

a. Aspirin, Valproic acid, Salicylic acid
b. Penicillin, Gentamicin, Metronidazole
c. Digoxin, Lidocaine, Propranolol
d. Acetaminophen, Ibuprofen, Naproxen

b. Decreased distribution

[PROTEIN BINDING]

Lidocaine + Epinephrine → ______

a. Increased distribution

b. Decreased distribution

a. Increased effect of morphine and verapamil

[ALTERATION OF BLOOD FLOW]

Beta blocker + Morphine & Verapamil → ________ due to decreased hepatic metabolism

a. Increased effect of morphine and verapamil

b. Decreased effect of morphine and verapamil

b. Decreased hepatic metabolism

[ALTERATION OF BLOOD FLOW]

Beta blocker + Morphine & Verapamil increases the effect of morphine and verapamil due to ______

a. Increased hepatic metabolism

b. Decreased hepatic metabolism

a. True

[ALTERATION OF BLOOD FLOW]

Metabolism may occur not only in the liver, but also in other organs (kidney, lungs, GIT)

a. True

b. False

• Liver

• Kidney

• Lungs

• GIT

METABOLISM may occur in _____ [4]

a. Hypertensive Crisis

[ALTERATION OF METABOLISM IN GIT]

MAOIs + Tyramine-rich food → ______

a. Hypertensive Crisis

b. Hypotensive Crisis

a. Bleeding

[ALTERATION OF GI FLORA]

Anticoagulant + antibiotic → decrease Vit K2 (Menoquinone) → ______

a. Bleeding

b. Coagulation

a. Increase toxicity

[ALTERATION OF GI FLORA]

Antibiotics + Digoxin → ______

a. Increase toxicity

b. Decrease toxicity

a. Decrease OCP effect

[ALTERATION OF GI FLORA]

OCP + antibiotic → _____

a. Decrease OCP effect

b. Decrease Antibiotic effect

c. Increase OCP effect

d. Increase Antibiotic effect

• Omeprazole

• Carbamazepine, charbroiled foods, cruciferous vegetables

• Rifampicin

• Alcohol (Chronic)

• Phenytoin

• Griseofulvin

• Phenobarbital

• Tolbutamide

• St. John’s Wort

📌Mnemonic: “O-CRAP-GPTS”

Enzyme Inducers

• Sodium valproate

• Isoniazid

• Cimetidine

• Ketoconazole

• Fluoroquinolones

• Alcohol (Acute) , Antivirals (Protease Inhibitors)

• Ciprofloxacin

• Erythromycin (except Azithromycin)

• Sulfonamides

• Diltiazem

• Grapefruit

• Disulfiram

• Quinidine /Quinine

• Chloramphenicol

📌Mnemonic: “SICK FACES DG. DQ. COM”

[STIMULATION / INHIBITION OF METABOLISM]

Enzyme Inhibitors

a. Increase immunosuppression

[PATHWAY INHIBITION]

Azathioprine + Allopurinol → ______

a. Increase immunosuppression

b. Decrease immunosuppression

• Ammonium chloride (NH4Cl)

• Ascorbic acid

[ALTERATION OF URINARY PH]

Example of Acidifying agents [2]

• Sodium bicarbonate (NaHCO₃)

• Acetazolamide

[ALTERATION OF URINARY PH]

Example of Alkalanizing agents [2]

a. Increase excretion of ASA

[ALTERATION OF URINARY PH]

ASA + NaHCO3 → ______

a. Increase excretion of ASA

b. Increase excretion of NaHCO3

a. Increase excretion of Amphetamine

[ALTERATION OF URINARY PH]

Amphetamine + NH4Cl → _____

a. Increase excretion of Amphetamine

b Increase excretion of NH4Cl

a. Blockade of tubular secretion

[ALTERATION OF ACTIVE TRANSPORT]

Probenecid + Penicillin & Methotrexate → _____

a. Blockade of tubular secretion
b. Increased tubular secretion
c. Increased glomerular filtration
d. Decreased protein binding