There are several possible mechanisms, including the inhibition of CYP3A4-mediated metabolism.As calcium channel blocker, nifedipine has a risk of causing gingival hyperplasia

Overdose
A number of persons have developed toxicity due to acute overdosage with nifedipine, either accidentally or intentionally, and via either oral or parenteral administration. The adverse effects include lethargy, bradycardia, marked hypotension and loss of consciousness. The drug may be quantified in blood or plasma to confirm a diagnosis of poisoning, or to assist in a medicolegal investigation following death. Analytical methods usually involve gas or liquid chromatography and specimen concentrations are usually in the 100-1000 μg/L range. [1]

Mechanism of action
Nifedipine is a calcium channel blocker. Although nifedipine and other dihydropyridines are commonly regarded as specific to the L-type calcium channel, they also possess nonspecific activity towards other voltage-dependent calcium channels.Nifedipine has additionally been found to act as an antagonist of the mineralocorticoid receptor, or as an antimineralocorticoid. History
Nifedipine (initially BAY a1040, then Adalat) was developed by the German pharmaceutical company Bayer, with most initial studies being performed in the early 1970s.The use of nifedipine and related calcium channel antagonists was much reduced in response to 1995 trials that mortality was increased in patients with coronary artery disease who took nifedipine. This study was a meta-analysis, and demonstrated harm mainly in short-acting forms of nifedipine (that could cause large fluctuations in blood pressure) and at high doses of 80 mg a day and more. Adalat was the first German pharmaceutical to be awarded the highly prestigious Prix Galien in 1980.
Colestipol (trade names Colestid, Cholestabyl) is a bile acid sequestrant used to lower blood cholesterol, specifically low-density lipoprotein (LDL). It is also used to reduce stool volume and frequency, and in the treatment of chronic diarrhea.Like cholestyramine, colestipol works in the gut by trapping bile acids and preventing them from being reabsorbed. This leads to decreased enterohepatic recirculation of bile acids, increased synthesis of new bile acids by the liver from cholesterol, decreased liver cholesterol, increased LDL receptor expression, and decreasing LDL in blood. Side effects
The following notable side effects may occur:
gastrointestinal tract disturbances, especially (mild, occasionally severe) constipation
sometimes increase in VLDL and triglyceride synthesis

Interactions
Colestipol can bind to a number of drugs and nutrients in the gut and inhibit or delay their absorption. Such substances include:
thiazide diuretics, furosemide
gemfibrozil
benzylpenicillin, tetracycline
digoxin
lipid-soluble vitamins (A, D, E, K)

Contraindications
Colestipol is contraindicated in hypertriglyceridemia (high level of triglycerides in the blood). Chemistry
Colestipol is a copolymer of diethylenetriamine (DETA) —or tetraethylenepentamine according to some sources— and epichlorohydrin. The structure drawing (top right) shows the DETA moieties in blue and the epichlorohydrin moieties in red. == Notes and references ==