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This article describes some common drug-drug interactions between prescrip-tion medications and over-the-counter medications that people with diabetesmight encounter. With each interaction listed, there is a description of how toappropriately manage it. Also, proper timing of the medications in relation tofood intake is described. The data presented are not all-inclusive but do detailthe common medications used in people with diabetes.
Prescribed Medications and OTCs:
Interactions and Timing Issues
control these concurrent disease states.
the risk for drug-drug interactions.
referred to as “significance rating A,” Diabetes Spectrum Volume 15, Number 4, 2002
Table 1. Significance Rating Scales
om Resear
in which the consequences may bebothersome but should not signifi- Source A4
Source B5
Severity of
Support from
Assigned Rating
Avoidance Risk
Consequences
Literature
h to Practice
Possible, or Unlikely. Established doc-umentation has been proven to occur in well-controlled studies. Probabledocumentation is very likely to occur lypharmac
y: Boon or Bane?
Table 2. Prescription Drug and OTC Interactions
Prescription Drug
Significance Rating
Description and
Management
Antihypertensive Agents
ACE INHIBITORSBenazepril (Lotensin), captopril (Prinivil, Zestril), ramipril(Altace), quinapril (Accupril) inhibitor–related cough. Case reports have occurred with topical application as well asinhaled capsaicin.
Benazepril, captopril, enalapril, High-dose salicylates inhibit prostacyclin synthesis, which may decrease the hypoten- sive and vasodilator effects of ACE inhib- reduce the dosage of aspirin or change to analternative agent.
emptying may alter the effect of ␤-blockers.
(Visken), propranolol (Inderal),timolol (Blocadren), sotalol(Betapace) Calcium salts may impair the absorption of ␤-blockers. Monitor for signs of decreased efficacy and adjust dosage if necessary.
gluconate, calciumlactate, dibasic calci- Diabetes Spectrum Volume 15, Number 4, 2002
Table 2. Prescription Drug and OTC Interactions, Cont.
Prescription Drug
Significance Rating
Description and
Management
Cimetidine may reduce hepatic clearance of bisoprolol, carteolol, metoprolol, ␤-blockers creating an increased effect.
propranolol, timolol, sotalol dosage if necessary or change to alternativehistamine2-blocker.
effect of ␤-blockers by inhibiting prosta- glandin synthesis. Monitor blood pressure and adjust ␤-blocker dosage if necessary.
High-dose salicylates may alter the effect of ␤-blockers by inhibition of prostaglandins.
Monitor blood pressure and adjust dosage if necessary or change to alternative agent.
CALCIUM-CHANNEL BLOCKERSDiltiazem (Cardizem, Cartia XL, When large doses of calcium salts are given, a reduction of the hypotensive effects of calci- vital signs and adjust dosages if necessary.
Diltiazem, nifedipine, nisoldipine, Cimetidine may increase the plasma concen- tration of calcium-channel blockers, creating an increase in hypotensive effects. Monitorblood pressure and adjust dosage if necessaryor change to alternative agent.
LOOP DIURETICSBumetanide (Bumex), ethacrynic loop diuretics. Monitor for reduction of effi- cacy and adjust loop diuretic dosage if neces- A decreased diuretic response may be possi- ble in patients with cirrhosis and ascites.
Monitor these patients for decreased effect THIAZIDE DIURETICSChlorothiazide (Diuril), chlor- Hypercalcemia may result from this combi- nation. Monitor serum calcium and for signs of hypercalcemia. Avoid excessive or pro- HydroDiuril, Oretic), indapamide gluconate, calcium longed administration of calcium salts.
NSAIDs may cause a mild reduction in anti- hydrochlorothiazide, indapamide, ibuprofen, hypertensive effects of thiazide-type diuretics by induction of sodium/water retention and inhibition of renal prostaglandin. Monitor blood pressure and adjust dosage if necessary.
Diabetes Spectrum Volume 15, Number 4, 2002
Table 2. Prescription Drug and OTC Interactions, Cont.
om Resear
Prescription Drug
Significance Rating
Description and
Management
Antidiabetic Agents
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Salicylates may enhance insulin secretion and (Diabenese), glipizide (Glucotrol), magnesium salicylate, may increase the effectiveness of sulfony- Chlorpropamide, glipizide, gly- Magnesium salts may enhance absorption of sulfonylureas, therefore increasing the hypo- glycemic effect. Monitor blood glucose and lypharmac
Reduced hepatic metabolism of sulfonylureas lead to increases in efficacy of sulfonylureas.
Monitor blood glucose levels and adjustdosages if necessary.
y: Boon or Bane?
Cimetidine increases metformin concentra-tions by reducing renal clearance, therebyincreasing the blood glucose–lowering effect.
Monitor blood glucose and adjust dosage ifnecessary or change to alternative histamine2antagonist.
Antihyperlipemic Agents
BILE AND SEQUESTRANTSCholestyramine (Questran, Bile acid sequestrants may decrease the effec- Prevalite), colestipol (Colestid), tiveness of NSAIDs. Take the NSAID either 2 hours before or 6 hours after the adminis-tration of the bile acid sequestrant.
Aspirin reduces the cutaneous flushing andincreases the plasma concentration of niacin.
*Italics indicate medications specifically reported in the literature affect blood pressure and circulation.
higher risk for drug-drug interactions.
Diabetes Spectrum Volume 15, Number 4, 2002
Table 3. OTC Drug-Disease Interactions
when the medication should beadministered with regard to meals.
Medication
Effect on Disease State
Typically this class of medication causes no detrimental effect on the disease state.
Typically this class of medication has no Niacin may increase blood glucose levels. priate adjustments if necessary or change Ephedrine, naphazoline,* oxymetazoline, Decongestants may increase blood detrimental effect on the disease state. *The products underlined represent the topical nasal decongestants. Systemic effects are less likely to occur with topical use. Table 4. Timing of Administration11
blood pressure. It would be prudentto counsel patients to read labels on Medication
Timing of Administration
these products to identify potentialinteractions.
Antidiabetic Agents
Take at the same time of day, usually in the May be given with a meal or upon awakening are stable and reasonably well con-trolled, the short-term use of OTC May be given 30 minutes before a meal or with a May be given 30 minutes before a meal or with a Take 30 minutes before a meal to improve May be given 30 minutes before a meal or with a May be given 30 minutes before a meal or with a May be given 30 minutes before a meal or with a interactions, diabetes health care pro-fessionals must also monitor for drug- Take with the first bite of each main meal Take with the first bite of each main meal take medications in regard to foodintake? Food may hinder absorption Take with meals to lessen gastrointestinal upset Diabetes Spectrum Volume 15, Number 4, 2002
Table 4. Timing of Administration11, Cont.
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Medication
Timing of Administration
Usually taken 15 minutes before meals but References
h to Practice
National Diabetes Statistics, www.niddk.nih.gov/ Pharmacotherapy Self Assessment Program. 4th ed. Book 3. Kansas City, Mo. American Collegeof Clinical Pharmacy, p. 113 Antihypertensive Agents
3Ferrill M: Clinically relevant drug interactions.
In Drug Facts and Comparisons News. St. Louis, Mo., Facts and Comparisons, Nov. 1999, p.
ypharmac
Tatro DS: Drug Interaction Facts. St. Louis, 5Hansten PD, Horn JR: Drug Interaction Analysis and Management. St. Louis, Mo., Facts y: Boon or Bane?
Hoopmann M, Welte T, Boger RH: Drug-druginteractions in medical patients: effects of in-hos- pital treatment and relation to multiple drug use.
Int J Clin Pharmacol Ther 38:504–513, 2000 7The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High ever, food may enhance the bioavailability Blood Pressure: The Sixth Report of the JointNational Committee on Prevention, Detection, Pressure (JNC-VI). NIH Publication No. 98- (Vascor), diltiazem, felodipine (Plendil), 8American Diabetes Association: Treatment of hypertension in adults with diabetes (PositionStatement). Diabetes Care 25 (Suppl.
9LeMar HJ Jr, Georgitis WJ: Effect of cold reme- dies on metabolic control of NIDDM. Diabetes Antihyperlipemic Agents
Konrad D, Sobetzko D, Schmitt B, Schoenle EJ: Insulin-dependent diabetes mellitus induced by the antitussive agent dextromethorphan (Letter).
Diabetologia 43:261–262, 2000 11Drug Facts and Comparisons. St. Louis, Mo.,Facts and Comparisons, April 2002 FIBRIC ACID DERIVATIVESClofibrate (Atromid), fenofibrate Kimberly R. Rhoades, RPh, CDE, is aclinical pharmacist with Kaiser Permanente—Colorado in Lakewood, high doses may be split between morningand evening Take with meals, usually in the evening; however, high doses may be split between morning and evening Diabetes Spectrum Volume 15, Number 4, 2002

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