Hydrochlorothiazide, Premarin, and Risperdal: Drug Information Guide
Hydrochlorothiazide (HCTZ)
a. Brand and Generic Name
- Generic name: Hydrochlorothiazide
- Brand names: Microzide, HydroDIURIL, various combination products
b. Dosage Forms
- Tablets: 12.5 mg, 25 mg, 50 mg
c. Pharmacologic Category
- Thiazide diuretic
d. FDA-Approved Indications
- Hypertension (alone or in combination with other antihypertensives)
- Edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid/estrogen therapy
e. Dosage and Frequency
- Hypertension: 12.5-50 mg once daily 1
- Edema: 25-100 mg daily in single or divided doses
f. Mechanism of Action
- Inhibits sodium and chloride reabsorption in the distal convoluted tubule, increasing excretion of sodium, chloride, water, potassium, and bicarbonate
g. Contraindications
- Anuria
- Hypersensitivity to sulfonamide-derived drugs
- Severe renal dysfunction
h. Adverse Effects
i. Drug Interactions
- Dofetilide (contraindicated) 2
- NSAIDs (decreased diuretic efficacy)
- Lithium (increased lithium levels)
- Digoxin (increased risk of digitalis toxicity due to hypokalemia)
- Antidiabetic agents (may require dose adjustment due to hyperglycemic effect)
j. Patient Counseling Points
- Take in the morning to prevent nighttime urination
- Monitor for signs of electrolyte imbalance (muscle weakness, cramps)
- May cause photosensitivity; use sun protection
- May increase blood glucose; diabetic patients should monitor glucose levels
- Report dizziness upon standing (orthostatic hypotension)
Premarin (Conjugated Estrogens)
a. Brand and Generic Name
- Brand name: Premarin
- Generic name: Conjugated estrogens
b. Dosage Forms
- Tablets: 0.3 mg, 0.45 mg, 0.625 mg, 0.9 mg, and 1.25 mg 3
c. Pharmacologic Category
- Estrogen hormone
d. FDA-Approved Indications
- Treatment of moderate to severe vasomotor symptoms associated with menopause
- Treatment of moderate to severe vulvar and vaginal atrophy associated with menopause
- Prevention of postmenopausal osteoporosis
- Treatment of hypoestrogenism due to hypogonadism, castration, or primary ovarian failure
- Palliative treatment of metastatic breast cancer in select men and postmenopausal women
- Palliative treatment of advanced androgen-dependent prostate cancer
e. Dosage and Frequency
- Menopausal symptoms: 0.3-1.25 mg daily
- Osteoporosis prevention: 0.3-0.625 mg daily
- Hypogonadism: 0.3-0.625 mg daily cyclically
- Advanced prostate cancer: 1.25-2.5 mg three times daily
f. Mechanism of Action
- Binds to nuclear estrogen receptors in estrogen-responsive tissues
- Increases synthesis of DNA, RNA, and proteins in target tissues
- Reduces release of gonadotropin-releasing hormone from hypothalamus
g. Contraindications
- Undiagnosed abnormal genital bleeding
- Known or suspected estrogen-dependent neoplasia
- Active or history of venous thromboembolism
- Active or recent arterial thromboembolic disease
- Liver dysfunction or disease
- Known protein C, protein S, or antithrombin deficiency
- Pregnancy
h. Adverse Effects
- Increased risk of endometrial cancer (when used without progestin)
- Increased risk of breast cancer
- Venous thromboembolism
- Stroke
- Coronary heart disease
- Gallbladder disease
- Nausea, vomiting
- Headache
- Weight changes
i. Drug Interactions
- CYP3A4 inducers (decreased estrogen effect)
- CYP3A4 inhibitors (increased estrogen effect)
- Thyroid replacement therapy (may require dose adjustment)
- Anticoagulants (altered anticoagulant effect)
j. Patient Counseling Points
- Use lowest effective dose for shortest duration
- Report abnormal vaginal bleeding immediately
- Increased risk of cardiovascular events and breast cancer
- Regular breast examinations and mammograms recommended
- Discontinue if jaundice, visual disturbances, or migraine occurs
- May affect laboratory test results
Risperdal (Risperidone)
a. Brand and Generic Name
- Brand name: Risperdal
- Generic name: Risperidone
b. Dosage Forms
- Tablets: 0.25 mg, 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg 4
- Oral solution: 1 mg/mL
- Orally disintegrating tablets: 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg
- Long-acting injection: 12.5 mg, 25 mg, 37.5 mg, 50 mg
c. Pharmacologic Category
- Atypical antipsychotic
d. FDA-Approved Indications
- Schizophrenia in adults and adolescents (13-17 years)
- Bipolar I disorder (manic or mixed episodes) in adults and children (10-17 years)
- Irritability associated with autistic disorder in children and adolescents (5-16 years)
e. Dosage and Frequency
- Schizophrenia (adults): Initial 1 mg twice daily, target dose 4-8 mg/day
- Schizophrenia (adolescents): Initial 0.5 mg once daily, target dose 3 mg/day
- Bipolar mania (adults): Initial 2-3 mg once daily, range 1-6 mg/day
- Bipolar mania (children/adolescents): Initial 0.5 mg once daily, target dose 2.5 mg/day
- Autism irritability: Initial 0.25 mg/day (< 20 kg) or 0.5 mg/day (≥ 20 kg), target dose 0.5-3 mg/day
f. Mechanism of Action
- Antagonist at dopamine D2 and serotonin 5-HT2A receptors 5, 6
- Also antagonizes alpha1 and alpha2 adrenergic receptors and H1 histamine receptors
- The combination of D2 and 5-HT2A antagonism is believed to improve both positive and negative symptoms of schizophrenia with reduced extrapyramidal effects
g. Contraindications
- Hypersensitivity to risperidone or any component of the formulation
h. Adverse Effects
- Extrapyramidal symptoms (dose-dependent) 2
- Weight gain
- Hyperglycemia and diabetes mellitus
- Hyperprolactinemia
- QT interval prolongation
- Orthostatic hypotension
- Sedation
- Tardive dyskinesia (with long-term use) 4
- Neuroleptic malignant syndrome (rare)
i. Drug Interactions
- CYP2D6 inhibitors (increased risperidone levels)
- Carbamazepine and other CYP3A4 inducers (decreased risperidone levels)
- Drugs that prolong QT interval (additive effect)
- CNS depressants including alcohol (enhanced CNS depression) 4
- Levodopa and dopamine agonists (antagonistic effect)
j. Patient Counseling Points
- Take as prescribed, do not adjust dose without consulting healthcare provider
- May cause orthostatic hypotension; rise slowly from sitting or lying position 4
- May impair judgment, thinking, or motor skills; use caution when operating machinery 4
- Report signs of high blood sugar (increased thirst, urination, hunger)
- Avoid alcohol while taking risperidone 4
- Use caution in hot weather and during exercise (risk of overheating)
- Report involuntary muscle movements immediately
- For women of childbearing potential, discuss pregnancy plans with healthcare provider 4