Phrenilin Forte Side Effects
Generic Name: acetaminophen / butalbital
Note: This page contains side effects data for the generic drug acetaminophen / butalbital. It is possible that some of the dosage forms included below may not apply to the brand name Phrenilin Forte.
For the Consumer
Applies to acetaminophen / butalbital: capsules, tablets
Check with your doctor if any of these most COMMON side effects persist or become bothersome:
Seek medical attention right away if any of these SEVERE side effects occur while taking acetaminophen / butalbital:
Dizziness; drowsiness; light-headedness; mild stomach pain; nausea; vomiting.
Severe allergic reactions (rash; hives; itching; difficulty breathing or swallowing; tightness in the chest; swelling of the mouth, face, lips, throat, or tongue); confusion; fainting; fast heartbeat; fever, chills, or persistent sore throat; intoxicated feeling; mental or mood changes; numbness or tingling; red, swollen, blistered, or peeling skin; seizures; severe or persistent drowsiness; shortness of breath; sluggishness; symptoms of liver problems (eg, dark urine, loss of appetite, pale stools, severe stomach pain; yellowing of the skin or eyes); unusual bruising or bleeding; unusual tiredness or weakness.
For Healthcare Professionals
Applies to acetaminophen / butalbital: oral capsule, oral tablet
Nervous system side effects including drowsiness, lightheadedness, dizziness, sedation, and an intoxicated feeling have been reported frequently from the use of butalbital. Headache and seizures have been reported infrequently. Mental confusion, excitement, or depression have also been reported due to either intolerance (primarily in elderly or debilitated patients) or due to an overdose of butalbital.[Ref]
Hepatic side effects including severe and sometimes fatal dose dependent hepatitis has been reported with the use of acetaminophen in alcoholic patients. Hepatotoxicity has been increased during fasting. Several cases of hepatotoxicity from chronic acetaminophen therapy at therapeutic doses have also been reported despite a lack of risk factors for toxicity.[Ref]
Alcoholic patients may develop hepatotoxicity after even modest doses of acetaminophen. In healthy patients, approximately 15 grams of acetaminophen is necessary to deplete liver glutathione stores by 70% in a 70 kg person. However, hepatotoxicity has been reported following smaller doses. Glutathione concentrations may be repleted by the antidote N-acetylcysteine. One case report has suggested that hypothermia may also be beneficial in decreasing liver damage during overdose.
In a recent retrospective study of 306 patients admitted for acetaminophen overdose, 6.9% had severe liver injury but all recovered. None of the 306 patients died.
A 19-year-old female developed hepatotoxicity, reactive plasmacytosis and agranulocytosis followed by a leukemoid reaction after acute acetaminophen toxicity.[Ref]
Gastrointestinal side effects including nausea, vomiting, and abdominal pain have been reported frequently with the use of butalbital. Gastrointestinal side effects are rare with acetaminophen use, except in alcoholics and after overdose. Cases of acute pancreatitis have been reported rarely with the use of acetaminophen.[Ref]
One study has suggested that acetaminophen may precipitate acute biliary pain and cholestasis. The mechanism of this effect may be related to inhibition of prostaglandin and alterations in the regulation of the sphincter of Oddi.[Ref]
Renal side effects have been rare with acetaminophen and have included acute tubular necrosis and interstitial nephritis. Adverse renal effects have been most often observed after overdose, after chronic abuse (often with multiple analgesics), or in association with acetaminophen-related hepatotoxicity.[Ref]
Acute tubular necrosis usually occurs in conjunction with liver failure, but has been observed as an isolated finding in rare cases. A possible increase in the risk of renal cell carcinoma has been associated with chronic acetaminophen use as well.
A recent case-control study of patients with end-stage renal disease suggested that long term consumption of acetaminophen may significantly increase the risk of end-stage renal disease particularly in patients taking more than two pills per day.[Ref]
Hypersensitivity side effects including anaphylaxis and fixed drug eruptions have been reported rarely in association with acetaminophen use.[Ref]
Hematologic side effects including rare cases of thrombocytopenia associated with acetaminophen have been reported. Acute thrombocytopenia has also been reported as having been caused by sensitivity to acetaminophen glucuronide, the major metabolite of acetaminophen. Methemoglobinemia with resulting cyanosis has also been observed in the setting of acute overdose.[Ref]
Dermatologic side effects including acetaminophen associated bullous erythema and purpura fulminans have been reported. Erythematous skin rashes associated with acetaminophen have been reported rarely. Acetaminophen has been associated with a risk of rare but potentially fatal serious skin reactions know as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP).[Ref]
Respiratory side effects including dyspnea have been reported frequently with the use of butalbital. A case of acetaminophen-induced eosinophilic pneumonia has been reported.[Ref]
Two cases hypotension have been reported following the administration of acetaminophen. Both patients experienced significant decreases in blood pressure. One of the two patients required pressor agents to maintain adequate mean arterial pressures. Neither episode was associated with symptoms of anaphylaxis. Neither patient was rechallenged after resolution of the initial episode.[Ref]
Cardiovascular side effects including several cases of hypotension have been reported following the administration of acetaminophen.[Ref]
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3. Zimmerman HJ, Maddrey WC "Acetaminophen (paracetamol) hepatotoxicity with regular intake of alcohol: analysis of instances of therapeutic misadventure." Hepatology 22 (1995): 767-73
4. Lee WM "Medical progress: drug-induced hepatotoxicity." N Engl J Med 333 (1995): 1118-27
5. Perneger TV, Whelton PK, Klag MJ "Risk of kidney failure associated with the use of acetaminophen, aspirin, and nonsteroidal antiinflammatory drugs." N Engl J Med 331 (1994): 1675-79
6. Kawada A, Hiruma M, Noguchi H, Ishibashi A "Fixed drug eruption induced by acetaminophen in a 12-year-old girl." Int J Dermatol 35 (1996): 148-9
7. Bougie DW, Benito AI, Sanchez-Abarca LI, Torres R, Birenbaum J, Aster RH "Acute thrombocytopenia caused by sensitivity to the glucuronide conjugate of acetaminophen." Blood 109 (2007): 3608-9
8. Shoenfeld Y, Shaklai M, Livni E, Pinkhas J "Thrombocytopenia from acetaminophen." N Engl J Med 303 (1980): 47
9. Filipe PL, Freitas JP, Decastro JC, Silva R "Drug eruption induced by acetaminophen in infectious mononucleosis." Int J Dermatol 34 (1995): 220-1
10. Brown G "Acetaminophen-induced hypotension." Heart Lung 25 (1996): 137-40
It is possible that some side effects of Phrenilin Forte may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.
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