SCENARIO 1:
25 year old lady presented to you with complain of upper respiratory track infection. Past medical history revealed that she was on oral contraceptive.
Rx
Tab. Citrizine dihydrochloride 5mg
(1 per oral. once a day)
Tab. Acetaminophen
(SOS)
Tab. Erythromycin 250mg
(1 per oral. 12 hours. 7 days)
INTERACTIONS:
i) Erythromycin decreases contraceptive effects of orally administered contraceptive by inhibiting the hydrolysis of contraceptive-conjugate in gut by killing normal flora of gut responsible for conjugate hydrolysis.
ii) Acetaminophen increases gastric irritation by inhibiting synthesis of prostaglandin responsible for the protection of gastric mucosa. Increased gastric acidity may result in acidic catalysis of erythromycin. Hence dose adjustment of erythromycin is required for desired therapeutic effect.
iii) Citrizine dihydrochloride is H1 antagonist may decrease gastric motility and decrease bioavailability of co-administered drug.
SCENARIO 2:
49 year old male is a patient of hypertension and is on following medication.
Rx
Tab. Carvedilol 2.5mg
(1 per oral once a day)
Tab. Terazosin 1mg
(1 per oral. O.N)
Tab. Simvastatin 10mg
(1 per oral. S.H)
Tab. Carbamezepine 200mg
(1/2 tablet per oral. p.d.s)
Tab. Aspirin 75mg
(1 per oral once a day)
Tab. Clopidogrel 75mg
(1 per oral once a day)
i) Find out interactions?
a) Carvedilol (beta1-antagonist) and Terazosin (alpha1- antagonist) synergized the cardio-vascular depressive effects leading to orthostatic hypertension.
b) Aspirin and Clopidogrel synergistically enhances gastric irritation effects.
c) Carbamezepine increases Aspirin metabolism by induction of hepatic metabolism enzymes and also act as displacer of aspirin from bounded plasma proteins.
ii) What does the use of Terazosin suggest?
a) Terazosin reduces peripheral resistance by blocking alpha1 adrenoreceptor in vascular smooth muscles hence increasing pulling of blood in venous bed, reducing cardiac pre and afterload and cardiac output to some extent. All events result in reducing blood pressure.
b) Terazosin also increases urinary outflow, thus used in patient with impaired urinary outflow (prostrate hypertrophy).
iii) What is use of Carbamezepine here?
Carbamezepine antagonizes CNS related side effects of Carvedilol which may be headache, confusion, schizophrenia and anxiety.
iv) Common use of statin? Which is the best statin give reason?
Statin is used to reduce the risk of coronary ischemia by inhibiting atherosclerosis by inhibiting intrinsic cholesterol synthesis.
Best statin is atrovastatin because of its long lasting therapeutic effects.
v) Status of patient?
Hypertension, ischemic heart disease, obstruction in urine, mental disturbance
SCENARIO 3:
A 60 year old woman presented to you with prescription at your pharmacy with the complaint of pharyngitis, she was prescribed.
Tab. Erythromycin 250mg
(Thrice a day)
Post medication history of that patient revealed thatshe was on:
Tab. Atenolol 50mg
(Per day)
Tab. Simvastatin 20mg
i) Are you happy with antibiotic use?
No, because for such a minor indication there is no need of giving antibiotic i.e Erythromycin with such a high dose.
Also concomitant use of macrolide (erythromycin) with statin is associated with high risk of myopathy (statin induced) as macrolide is a potent Cyt P450 inhibitor and statins a re metabolized by this system.
ii) Command the use of statin?
Statin reduces the risk of deposition of fats (cholesterol) in vessels. Thus helps in keeping normal blood supply to heart.
iii) Command use of atenolol?
Atenolol is beta1-selective antagonist. It decreases cardiac activity and cardiac oxygen demand.
iv) Comment on the use of Atenolol and Simvastatin?
Post medical history indicatesthat patient had a problem of hypertension, therefore, Atenolol is used to control the B.P. Simvastatin is given to prevent the formation of clot, so to minimize the chance of myocardial infarction.
v) How would you counsel the patient regarding the use of Simvastatin?
Patient should take cholesterol restricted diet.
Patient should the regular exercise.
vi) what is the best time to take the statins? give the reason?
Statins should be taken at night. It off-sets a nocturnal increase in cholesterol synthesis.
SCENARIO 4:
65 year old male history of congestive heart failure and diabetes mellitus.
Rx
Tab. Diltiazem 90mg SR
(1 daily)
Tab. Lisinopril 5mg
(1 daily)
Tab. Atenolol 50mg
(1 daily)
Tab. Aspirin 75mg
(1 daily)
Tab. Simvastatin 10 mg
(1 daily)
Human insulin regular
(20 units’ morning and evening)
Tab. Metformin 500mg
(Thrice a day)
i) Find out interactions?
a) Beta blocker (atenolol) and insulin: Enhanced hypoglycemic response. Beta blocker inhibits glucose recovery from hypoglycemia, inhibition of symptoms of hypoglycemia (except sweating), increased blood pressure during hypoglycemia.
b) Diltiazem, atenolol and simvastatin leads to hypoglycemia.
c) Insulin and metformin interacts pharmacologically and leads to hypoglycemia.
ii) Timing of each medicine?
a) Insulin morning and evening during just or before meal.
b) Diltiazem and lisinopril after breakfast (9 am)
c) Metformin before lunch (1 pm)
d) Aspirin, simvastatin after dinner ( 9 pm)
e) Atenolol just before sleep.
iii) Rationale of each drug use?
a) Diltiazem and atenolol used to decrease cardiac oxygen demand.
b) Aspirin and simvastatin used to maintain proper blood supply to heart.
c) Lisinopril is used to excrete excessive water.
d) Insulin and metformin are used as anti-diabetic.
SCENARIO 5
Rx
Tab. Bendroflumethiazide 2.5mg
(1 daily)
Tab. Frusimide 40mg
(twice daily)
Tab. Enalpril 10mg
(1 daily)
Tab. Digoxin 125ug
(thrice daily)
Tab. Warfarin 5mg
(1 daily)
Tab. Co-proxamol
(1 prn)
i) Find interaction?
a) Frusimide and enalpril pharmacodynamically results in marked disturbance of electrolyte balance (hyperkalemia).
b) Digoxin may decrease gastro intestinal absorption of orally administered drugs.
c) The action of oral anti coagulant may be increased.
ii) Time of medication?
a) Warfarin early morning before or during breakfast.
b) Digoxin, frusimide and enalpril after breakfast ( 9 am)
c) Digoxin and bendroflumethazine after lunch (1 pm)
d) Digoxin and frusimide after dinner ( 9 pm)
iii) Status of patient?
a) Congestive heart failure
b) Angina pectoris
c) Odematous state.
iv) Why co-proxamol is prescribed?
Co-proxamol is prescribed to overcome the pain associated with congestive heart failure. It is centrally and peripherally acting analgesic agent.
v) Comment on the condition of the patient on the drugs prescribed?
Congestive heart failure: Bendroflumethiazide and Frusemide are given to cause diuresis to prevent the edema associated with CHF.
Analpril is ACE inhibitor and is given to decrease worn-load of the heart.
Digoxin causes +ve inotropic, chronotropic effect i.e. to increase the strength of contraction of myocardial muscles to increase the cardial output.
RATIONALE:
a) Bendroflumethiazide:
It is a loop diuretic and will cause hypokalemia so:
Monitor K-levels.
Give a K supplement if necessary.
It is a safe drug and does not cause any abrupt fall in B.P. even if dose increased by 2.5 g/day.
b) Frusemide:
It is a loop diuretic and will cause hypocalemia so:
Monitor K-levels.
Give K supplement.
c) Analpril:
It will cause severe hypotension, which can occur after initial doses of any ACE-inhibitor in patienes who are hypovolemic due to diuretics, salt restriction, or GIT fluid losses. So it shoukd be given at night.
d) Digoxin:
Carefully monitor the patient because he is already on diuretic therapy associated with electrolyte imbalance otherwise it will enhance the arrhythmic potential of Digoxin.
e) Warfarin
Closely monitor the coagulation indices. Continue use of anti coagulant(oral) and thiazide diuretic because of displacement of Warfarin with Albumin. Bendroflumethiazide enhances the effect of Warfarin.
