Cog·nex (k g n ks ) A trademark for the drug tacrine hydrochloride. |
Cognex,
tacrine hydrochloride
Cognex
Pharmacologic class: Cholinergic (cholinesterase inhibitor)
Therapeutic class: Anti-Alzheimer's agent
Pregnancy risk category C
Action
Inhibits acetylcholine breakdown in cerebral cortex, increasing acetylcholine levels
Availability
Capsules: 10 mg, 20 mg, 30 mg, 40 mg
⊘Indications and dosages
➣ Mild to moderate dementia of Alzheimer's disease
Adults: 10 mg P.O. q.i.d. for 4 weeks. If alanine aminotransferase (ALT) level doesn't change, increase to 20 mg q.i.d. As tolerated, increase incrementally at 4-week intervals, up to 160 mg/day (30 to 40 mg P.O. q.i.d.).
Dosage adjustment
• Elevated transaminase levels
Contraindications
• Hypersensitivity to drug or other acridine derivatives
• Jaundice with previous tacrine therapy
• Bilirubin level above 3 mg/dl
• Hypersensitivity symptoms accompanied by transaminase elevations
Precautions
Use cautiously in:
• sick sinus syndrome, bradycardia, hepatic or renal disease, bladder obstruction, asthma, seizure disorders, prostatic hyperplasia
• history of ulcers or increased risk of GI bleeding (as from concurrent use of nonsteroidal anti-inflammatory drugs)
• pregnant or breastfeeding patients
• children.
Administration
• Preferably, give 1 hour before or 2 hours after meals. However, if GI upset occurs, drug can be given with meals (although food slows its absorption).
| Route | Onset | Peak | Duration |
| P.O. | Unknown | 1-2 hr | Unknown |
Adverse reactions
CNS: dizziness, headache, confusion, insomnia, tremor, ataxia, drowsiness, anxiety, agitation, depression, hallucinations, hostility, abnormal thinking, fatigue, malaise
CV: hypotension, hypertension, chest pain, peripheral edema
EENT: conjunctivitis, rhinitis, sinusitis, pharyngitis
GI: nausea, vomiting, diarrhea, constipation, dyspepsia, abdominal pain, anorexia
GU: urinary frequency or incontinence, urinary tract infection
Musculoskeletal: back pain, myalgia
Respiratory: upper respiratory infection, cough, bronchitis, pneumonia, dyspnea
Skin: rash, flushing, purpura
Other: chills, fever
Interactions
Drug-drug. Anticholinergics: interference with anticholinergic action
Cholinergics (including bethanechol), succinylcholine: synergistic effects
Cimetidine: increased tacrine blood level
Theophylline: increased theophylline blood level, greater risk of toxicity
Drug-diagnostic tests. Hepatic enzymes: increased levels
Drug-food. Any food: decreased tacrine bioavailability
Patient monitoring
• Monitor neurologic status to assess drug efficacy and determine optimal dosage.
• Check ALT level weekly for first 18 weeks. If level doesn't change markedly by end of this period, monitor level every 3 months. Otherwise, continue weekly monitoring.
Patient teaching
• Tell patient or caregiver that drug should be taken 1 hour before or 2 hours after meals.
• Advise caregiver to monitor patient's neurologic status carefully and to use safety measures at home to prevent injury.
• Recommend small, frequent servings of food and adequate fluid intake to minimize GI upset.
• Explain that drug doesn't change underlying dementia but may improve symptoms or slow further deterioration.
☞ Stress importance of taking drug as prescribed. Caution against sudden dosage decreases or abrupt withdrawal.
• Tell patient or caregiver that if drug is stopped for 4 weeks or longer, dosage adjustment and monitoring schedule should be discussed with prescriber before restarting.
• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.
Cognex®
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