Nifedipine sustained-release

Isoptin SR, Verelan) 180-480 Amlodipine (Norvasc) 5-10 Nifedipine long-acting (Adalat CC, Procardia XL) 30-90 Diltiazem sustained-release (Cardizem SR) 180-360 Diabetes... 

Short-acting nifedipine may rarely cause an increase in the frequency, intensity, and duration of angina in association with acute hypotension. This effect may be obviated by using sustained-released formulations of nifedipine or other dihydropyridines. Other side effects of dihydropyridines include dizziness, flushing, headache, gingival hyperplasia, and peripheral edema. Side effects due to vasodilation such as dizziness, flushing, head-... 

Indications for nifedipine include angina pectoris (p. 308) and, — when applied as a sustained release preparation,... 

Angina patients maintained on the nifedipine capsule formulation may be switched to the sustained release tablet at the nearest equivalent total daily dose. Experience with doses more than 90 mg in angina is limited. 

Answer Nifedipine, unless formulated for slow, sustained release, is characterized by relatively rapid onset of vasodUatory effects. This man s side effects reflect the rapid and intense fall in blood pressure and consequent reflex increases in sympathetic tone. The increase in anginal episodes also is a result of drug-induced periodic increases in heart rate. 

Oral sustained-release (Cardene SR) 30, 45, 60 mg capsules Parenteral (Cardene I.V.) 0.1, 2.5 mg/mL for injection Nifedipine (generic, Adalat, Procardia)... 

Remunan C, Bretal MJ, Nunez A, Jato JLY. Accelerated stability study of sustained-release nifedipine tablets prepared with Gelucire. Int J Pharm 1992 80 151-159. 

Compliance. Multidrug therapy poses a substantial problem of compliance. Since treatment will be lifelong it is well worthwhile taking the trouble to find the most convenient regimen for each individual. A single daily dose would be ideal and to achieve this sustained-release formulations and fixed-dose combinations are used. Examples include Tenoretic (atenolol + chlortalidone), Tenif (atenolol + nifedipine) and Zestoretic (lisinopril + hydrochlorothiazide). 

In the past, the difficulties presented in the administration of drugs in the treatment of hypertensive emergencies were largely overcome with the use of nifedipine administered sublingually. The onset of action was rapid, and the drug was also used sublingually for the treatment of acute attacks of angina pectoris. Presently, two types of formulation of nifedipine are available, both intended primarily for peroral administration. The sustained-release formulation is... 

Pfizer s Procardia XL is a once daily calcium channel blocker (CCB) for hypertension and angina. It delivers nifedipine via Alza s osmotic pump, a patented high-tech sustained-release (SR) formulation. Several generic companies are currently seeking FDA approval for an A/B substitute using low-tech SR formulations. The generic companies claim that they are not infringing Pfizer s patent estate, which includes ... 

There are approximately a dozen calcium channel antagonists marketed in the United States for the treatment of hypertension, certain dysrhythmias, and some forms of angina (see Chaps. 13,15, and 17). The calcium channel blockers are classified by their chemical structure as phenylalkylamines (e.g., verapamil), benzothiapines (e.g., diltiazem), and dihydropyridines (e.g., amlodipine, felodipine, nicardipine, and nifedipine). Several of these agents, namely, diltiazem, nicardipine, nifedipine, and verapamil, are formulated as sustained-release oral dosage forms or have a slow onset of action and longer half-life (e.g., amlodipine " ), allowing once-daily administration. 

To protect its 745 roil. Cardizem franchise, Marion Merrell Dow apparently intends to follow a strategy similar to the one Pfizer used to protect its nifedipine franchise from generics with sustained-release Procardia XL. Pfizer s strategy called for discounting the new generation product by 25 percent and promoting the price savings directly to consumers. Pfizer told analysts last fail that Procardia XL accounted for nearly two-thirds of all Procardia scripts one year after its launch in October 1989 ( The Pink Sheet nov. 5, p. 8). 

Nifedipine (10 to 20 mg t.i.d.) is indicated in vasospastic (Prinzmetal s or variant) angina. It may also be used in chronic stable angina (classical effort-associated angina) without vasospasm. Sustained release nifedipine (30 to 60 mg once daily) is used in hypertension. 

Several studies have raised concerns about the long-term safety of short-acting nifedipine. The proposed mechanism for this adverse effect lies in abrupt vasodilation with reflex sympathetic activation. There does not appear to be either significant reflex tachycardia or long-term adverse outcomes from treatment with sustained-release forms of nifedipine or with dihydropyiidine Ca blockers such as amlodipine or felodipine, which have more favorable (slower) pharmacokinetics. 

Sustained-release clonidine 250 micrograms daily for 2 weeks increased the hypotensive effects of nifedipine 20 mg twice daily by about 5 mmHg (mean blood pressure reduction) in 12 patients. Clonidine did not alter the slight heart rate increase seen with nifedipine. In a clinical trial in 39 patients with hypertension inadequately controlled by nifedipine GITS 30 to 60 mg daily, transdermal clonidine successfully decreased blood pressure in all 35 patients who completed a one-week titration phase then an 8-week maintenance phase. ... 

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