Nifedipine dosing

Furberg CD, Psaty BM, Meyer JV. Nifedipine. Dose-related increase in mortality in patients with coronary heart disease. Circulation 1995 92(5) 1326-31. 

Although information is limited, these pharmacokinetic interactions are predictable, and potentially serious. To date, clinically relevant increases in calcium-channel blocker levels or effects have been shown for nelfinavir with nifedipine or felodipine, indinavir/ritonavir with amlodipine, diltiazem or nifedipine, and atazanavir with diltiazem. Caution would be required with any of these combinations, anticipating the need to use lower doses of the calcium-channel blocker. The manufacturers specifically recommend that if diltiazem is given with atazanavir the initial dose of diltiazem should be reduced by 50% with subsequent dose titration and ECG monitoring. They also note that verapamil levels may be raised and therefore advise caution. Similarly, the manufaeturers of nifedipine say that blood pressure monitoring is required and a reduction in nifedipine dose may be neeessary if it is given with HIV-protease inhibitors. However, some UK manufacturers (e.g. felodipine, lercanidipine, nimodipine ) recommend avoiding the concurrent use of ritonavir and other protease inhibitors if possible. 

Nifedipine An increase in nifedipine levels with increased nifedipine effects seen, probably due to increased absorption. Monitor patient and adjust the nifedipine dose accordingly. 34... 

The performance of this system is shown in Figure 17 for the release of nifedipine from the GITS system [47], The reproducibility of the release rates is remarkable. Also note that the fractions released over time from three separate doses are basically superimposable. It should also be noted that these systems have an inherent delay in the onset of drug delivery which arises from the time required to build up a sufficient hydrostatic pressure to permit release of the gel that is formed within the tablet during delivery. Figure 18 shows the comparison of the in vitro and in vivo cumulative fraction released for the 30 mg system. Clearly, the in vitro performance is mirrored in the in vivo data. 

Nifedipine is associated with fewer side effects than magnesium or ft-agonist therapy. Five to 10 mg nifedipine may be administered sublingually every 15 to 20 minutes for three doses. Once stabilized, 10 to 20 mg may be administered by mouth every 4 to 6 hours for preterm contractions. 

GI absorption of many poorly soluble drugs depends on small intestinal transit, as demonstrated for ketoprofen, nifedipine, haloperidol, miconazole, and others. Small intestinal transit rate and transit time become important factors in drug absorption, particularly when the ratio of dose to solubility is high and dissolution rate is very slow or when the drug is... 

NiFEDiPiNE Individualize dosage. Excessive doses can result in hypotension. 

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. 

Uses Infxns of the resp tract, skin, bone, urinary tract Action 3rd-gen cephalosporin -1- cell wall synth Dose Adults. 400 mg PO daily-bid Peds. 8-20 mg/kg/d PO daily—bid -1- in renal impair Caution [B, +] Contra Cephalosporin allergy Disp Susp SE N/V/D, flatulence, abd pain Interactions t Nqjhrotox W/ aminoglycosides, loop diuretics t effects W/ nifedipine, probenecid EMS t Risk of nephrotox w/ loop diuretics monitor for signs of electrolyte disturbances and hypovolemia d/t D monitor pt for super Infxn OD May cause N/V/D, Szs, muscles spasms symptomatic and supportive... 

Deravirdine (Rescnptor) [Antiretroviral/NNRTI] Uses HIV Infxn Action Nonnucleoside RT inhibitor Dose 400 mg PO tid Caution [C, ] CDC recommends HIV-infected mothers not to breast-feed (transmission risk) w/ renal/hepatic impair Contra Use w/ drugs dependent on CYP3A for clearance (Table VI-8) Disp Tabs SE Fat redistribution, immune reconstitution synd, HA, fatigue, rash, T transaminases, N/V/D Interactions T Effects W/ fluoxetine T effects OF benzodiazepines, cisapride, clarithromycin, dapsone, ergotamine, indinavir, lovastatin, midazolam, nifedipine, quinidine, ritonavir, simvastatin, terfena-dine, triazolam, warfarin effects W/ antacids, barbiturates, carbamazepine, cimetidine, famotidine, lansoprazole, nizatidine, phenobarbital, phenytoin, ranitidine, rifabutin, rifampin effects OF didanosine EMS Use of benzodiazepines and CCBs should be avoided may cause a widespread rash located on upper body and arms OD May cause an extension of nl SEs symptomatic and supportive Deferasirox (Exjade) [Iron Chelator] Uses Chronic iron overload d/t transfusion in pts >2 y Action Oral iron chelator Dose Initial 20 mg/kg... 

T Pancreatic insulin release Metformin Peripheral insulin sensitivity hepatic glucose output/production i intestinal glucose absorption Dose Ist-line (naive pts), 1.25/250 mg PO daily-bid 2nd-line, 2.5/500 mg or 5/500 mg bid (max 20/2000 mg) take w/ meals, slowly T dose hold before 48 h after ionic contrast media Caution [C, -] Contra SCr >1.4 mg/dL in females or >1.5 mg/dL in males hypoxemic conditions (sepsis, recent MI) alcoholism metabolic acidosis liver Dz Disp Tabs SE HA, hypoglycemia, lactic acidosis, anorexia, N/V, rash Additional Interactions T Effects W/ amiloride, ciprofloxacin cimetidine, digoxin, miconazole, morphine, nifedipine, procainamide, quinidine, quinine, ranitidine, triamterene,... 

Generally, the dihydropyridine CCBs have evolved into three distinct subclasses based on their pharmacokinetics and pharmacodynamics. Early dihydropyridines such as nifedipine and nicardipine are characterized by a rapid onset of action and short duration of action due to limited half-life lives, thus requiring twice-daily dosing (Bayer, 2004). In addition, these short-acting compounds may have potential detrimental effects... 

Labetalol, an a- and /i-blocker, has been used in hourly doses of 100-200 mg. It has reduced BP as effectively as oral nifedipine and acts more slowly and effectively. 

Hypertensive crises are characterized initially by headache, but can evolve to include neck stiffness, chest discomfort, palpitations, confusion, and, ultimately, hemorrhage or stroke. Treatment of MAOI-associated hypertension may include a watch-and-wait stance by the patient if the symptoms are mild. Some patients have the ability to check and monitor their own blood pressure. Others may consult with a physician for blood pressure checks and observation, but if symptoms are severe, the patient may need to go to an emergency room or self-medicate. Standard emergency room treatment is intravenous phentolamine, an a-adrenergic blocker, continuous monitoring and management until blood pressure is normalized without medication. Some doctors will provide patients with small doses of chlorpromazine or nifedipine to treat hypertension if a problem arises. 

Self-medication of a MAOI-induced hypertensive crisis is controversial. In a hypertensive crisis the lack of access to medical services may lead to even greater complications. A small dose of medication taken as part of a larger plan to blunt the rise in blood pressure may prevent serious complications. However, headache is common, has multiple causes, and patients may not accurately identify a headache due to hypertension without a blood pressure check. In addition, selfadministration of nifedipine, especially sublingually, may result in needless and perhaps dangerous drops in blood pressure. 

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