Allergic hypersensitivity reactions have occurred rarely after parenteral doses of the vitamin B12
compounds, cyanocobalamin and hydroxocobalamin. Antibodies to hydroxocobalamin-transcobalamin II complex have developed during hydroxocobalamin therapy. Arrhythmias secondary to hypokalemia have occurred at the beginning of parenteral treatment with hydroxocobalamin. Intranasal cyanocobalamin may cause rhinitis, nausea and headache.
Cyanocobalamin or hydroxocobalamin should, if possible, not be given to patients with suspected vitamin B12
deficiency without 1st confirming the diagnosis. Regular monitoring of the blood is advisable. Use of doses >10 mcg daily may produce a hematological response in patients with folate deficiency; indiscriminate use may mask the precise diagnosis. Conversely, folate may mask vitamin B12
deficiency. Cyanocobalamin should not be used for Leber's disease or tobacco amblyopia since these optic neuropathies may degenerate further.
The most common adverse effects reported during therapy with pregabalin are dizziness and somnolence. Other common adverse effects include blurred vision, diplopia, increased appetite and weight gain, dry mouth, constipation, vomiting, flatulence, euphoria, confusion, reduced libido, erectile dysfunction, irritability, vertigo, ataxia, tremor, dysarthria, paraesthesia, fatigue and edema. Disturbances of attention, memory, coordination and gait also occur frequently. Syncope and congestive heart failure have been reported less frequently. Reversible renal failure, elevation of creatine kinase concentration and rhabdomyolysis have been reported rarely. Hypersensitivity reactions have occurred shortly after starting pregabalin therapy; symptoms include rash, blisters, urticaria, dyspnea and wheezing. Stevens-Johnson syndrome has also been reported. An increased incidence of hemangiosarcoma was observed in mice that had been given high doses of pregabalin.