Adalat CR Special Precautions

Care must be exercised in patients with very low blood pressure (severe hypotension with systolic pressure less than 90 mm Hg), in cases of manifest heart failure and in the case of severe aortic stenosis.
There are no safety and efficacy data from well-controlled studies in pregnant women.
Animal studies have shown a variety of embryotoxic, placentotoxic and fetotoxic effects (see Pharmacology: Toxicology: Preclinical Safety Data under Actions) when administered during and after the period of organogenesis.
From the clinical evidence available a specific prenatal risk has not been identified. Although an increase in perinatal asphyxia, caesarean delivery as well as prematurity and intrauterine growth retardation have been reported. It is unclear whether these reports are due to the underlying hypertension, its treatment or to a specific drug effect.
The available information is inadequate to rule out adverse drug effects on the unborn and newborn child. Therefore any use in pregnancy after week 20 requires a very careful individual risk benefit assessment and should only be considered if all other treatment options are either not indicated or have failed to be efficacious.
Careful monitoring of blood pressure must be exercised, also when administered nifedipine with i.v. magnesium sulfate, owing to the possibility of an excessive fall in blood pressure which could harm both mother and fetus.
As with other non-deformable material (see Instructions for Use/Handling under Cautions for Usage) care should be used when administering Adalat CR in patients with pre-existing severe gastrointestinal narrowing because obstructive symptoms may occur. Bezoars can occur in very rare cases and may require surgical intervention.
In single cases obstructive symptoms have been described without known history of gastrointestinal disorders.
When doing barium contrast X-ray Adalat CR may cause false positive effects (e.g. filling defects interpreted as polyp).
In patients with impaired liver function careful monitoring and, in severe cases, a dose reduction may be necessary (see Pharmacology: Pharmacokinetics under Actions).
Nifedipine is metabolised via the cytochrome P450 3A4 system. Drugs that are known to either inhibit or to induce this enzyme system may therefore alter the first pass or the clearance of nifedipine (see Interactions).
Drugs, which are inhibitors of the cytochrom P450 3A4 system and therefore may lead to increased plasma concentrations of nifedipine are, e.g.: Macrolide antibiotics (e.g., erythromycin), anti-HIV protease inhibitors (e.g., ritonavir), azole antimycotics (e.g., ketoconazole), the antidepressants nefazodone and fluoxetine, quinupristin/dalfopristin, valproic acid, cimetidine.
Upon co-administration with these drugs, the blood pressure should be monitored and, if necessary, a reduction of the nifedipine dose should be considered.
For use in special populations, see Dosage & Administration.
In-Vitro Fertilization: In single cases of in vitro fertilization calcium antagonists like nifedipine have been associated with reversible biochemical changes in the spermatozoa's head section that may result in impaired sperm function. In those men who are repeatedly unsuccessful in fathering a child by in vitro fertilization, and where no other explanation can be found, calcium antagonists like nifedipine should be considered as possible causes.
Effects on Ability to Drive and Use Machines: This drug can impair the ability to drive or to operate machinery (see Adverse Reactions). This applies particularly at the start of the treatment, on changing the medication and in combination with alcohol. However, reactions to the drug vary in intensity from individual to individual.