classification

PHARMACOTHERAPEUTIC: Antiviral. CLINICAL: Antiherpetic agent (see p. 71C).

Action

Converted to acyclovir triphosphate, becoming part of viral DNA chain. Therapeutic Effect: Interferes with DNA synthesis, replication of herpes simplex virus (HSV), varicella-zoster virus (VZV).

Pharmacokinetics

Rapidly absorbed after PO administration. Protein binding: 13%–18%. Rapidly converted by hydrolysis to active compound acyclovir. Widely distributed to tissues, body fluids (including CSF). Primarily eliminated in urine. Removed by hemodialysis. Half-life: (acyclovir) 2.5–3.3 hrs (increased in renal impairment).

Uses

Treatment of herpes zoster (shingles) in immunocompetent adults. Treatment of initial and recurrent genital herpes in immunocompetent adults. Prevention of recurrent genital herpes and reduction of heterosexual transmission of genital herpes. Suppression of genital herpes in HIV-infected pts. Treatment of cold sores, chickenpox in immunocompetent children. OFF-LABEL: Prophylaxis and treatment of cancer-related HSV, VZV.

Precautions

Contraindications: Hypersensitivity to or intolerance of acyclovir, valacyclovir, or their components. Cautions: Renal impairment, concurrent use of nephrotoxic agents.

 ​Lifespan considerations

Pregnancy/Lactation: May cross placenta. May be distributed in breast milk. Pregnancy Category B. Children: Safety and efficacy not established. Elderly: Age-related renal impairment may require dosage adjustment.

Interactions

DRUG: Nephrotoxic medications (e.g., ACE inhibitors, aminoglycosides, IV contrast media) may increase risk of nephrotoxicity, renal impairment. HERBAL: None significant. FOOD: None known. LAB VALUES: None significant.

Availability (Rx)

Caplets: 500 mg, 1,000 mg. Tablets: 500 mg, 1,000 mg.

• Give without regard to meals. • If GI upset occurs, give with meals.

PO: ADULTS, ELDERLY: 1 g 3 times a day for 7 days.

Side effects

Frequent: Herpes zoster (17%–10%): Nausea, headache. Genital herpes (17%): Headache. Occasional: Herpes zoster (7%–3%): Vomiting, diarrhea, constipation (50 yrs and older), asthenia (loss of strength, energy), dizziness (50 yrs and older). Genital herpes (8%–3%): Nausea, diarrhea, dizziness. Rare: Herpes zoster (3%–1%): Abdominal pain, anorexia. Genital herpes (3%–1%): Asthenia (loss of strength, energy), abdominal pain.

Adverse effects/toxic reactions

Neutropenia, thrombocytopenia, renal failure occur rarely.

Question for history of allergies, particularly to valacyclovir, acyclovir. Tissue cultures for herpes zoster, herpes simplex should be obtained before giving first dose (therapy may proceed before results are known). Assess medical history, esp. HIV infection, bone marrow or renal transplantation, renal/hepatic impairment.

classification

PHARMACOTHERAPEUTIC: Synthetic nucleoside. CLINICAL: Antiviral (see p. 71C).

Action

Competes with viral DNA esterases, is incorporated directly into growing viral DNA chains. Therapeutic Effect: Interferes with DNA synthesis, viral replication.

Pharmacokinetics

Well absorbed, rapidly converted to ganciclovir by intestinal mucosal cells and hepatocytes. Widely distributed including CSF, ocular tissue. Slowly metabolized intracellularly. Primarily excreted in urine. Removed by hemodialysis. Half-life: Ganciclovir: 4 hrs (increased in renal impairment).

Uses

Adults: Treatment of cytomegalovirus (CMV) retinitis in AIDS. Prevention of CMV disease in high-risk renal, cardiac, renal-pancreas transplant pts. Children: Prevention of CMV disease in high-risk renal and cardiac transplant pts.

Precautions

Contraindications: Hypersensitivity to acyclovir, ganciclovir. Cautions: Extreme caution in children because of long-term carcinogenicity, reproductive toxicity. Renal impairment, concurrent nephrotoxic medications, preexisting bone marrow suppression or cytopenias, history of cytopenic reactions to other drugs, elderly (at greater risk for renal impairment).

 ​Lifespan considerations

Pregnancy/Lactation: Effective contraception should be used during therapy; valganciclovir should not be used during pregnancy. Avoid breastfeeding; may be resumed no sooner than 72 hrs after last dose of valganciclovir. Pregnancy Category C. Children: Safety and efficacy not established in those younger than 12 yrs. Elderly: Age-related renal impairment may require dosage adjustment.

Interactions

DRUG: Bone marrow depressants may increase myelosuppression. May increase risk of toxicity of didanosine, mycophenolate. Probenecid may decrease renal clearance, increase concentration. Zidovudine (AZT) may increase risk of hematologic toxicity. HERBAL: None significant. FOOD: All foods maximize drug bioavailability. LAB VALUES: May decrease creatinine clearance, platelet count, neutrophils, Hgb, Hct. May increase serum creatinine.

Availabilities (Rx)

Powder for Oral Solution: 50 mg/ml (100 ml).

Tablets: 450 mg.

• Do not break, crush tablets; give whole (potential carcinogen). • Avoid contact with skin. • Wash skin with soap, water if contact occurs. • Give with food. • Store oral suspension in refrigerator. Discard after 49 days.

PO: ADULTS: Initially, 900 mg (two 450-mg tablets) twice daily for 21 days. Maintenance: 900 mg once daily.

Side effects

Frequent (16%–9%): Diarrhea, neutropenia, headache. Occasional (8%–3%): Nausea. Rare (Less Than 3%): Insomnia, paresthesia, vomiting, abdominal pain, fever.

Adverse effects/toxic reactions

Hematologic toxicity, including severe neutropenia (most common), anemia, thrombocytopenia, leukopenia, aplastic anemia, pancytopenia, bone marrow suppression may occur. Retinal detachment occurs rarely. Overdose may result in renal toxicity. May decrease sperm production, fertility.

Obtain baseline CBC, serum chemistries, renal function, urinalysis. Receive full medication history.

classification

PHARMACOTHERAPEUTIC: Carboxylic acid derivative. CLINICAL: Anticonvulsant, antimanic, antimigraine (see p. 37C).

Action

Directly increases concentration of inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Therapeutic Effect: Produces anticonvulsant effect, stabilizes mood, prevents migraine headache.

Pharmacokinetics

Well absorbed from GI tract. Protein binding: 80%–90%. Metabolized in liver. Primarily excreted in urine. Not removed by hemodialysis. Half-life: 9–16 hrs (may be increased in hepatic impairment, elderly, children younger than 18 mos).

Uses

Treatment of simple and complex absence (petit mal) seizures (monotherapy preferred due to unpredictable interactions, increased risk of hepatotoxicity). Adjunctive therapy of multiple seizures (Stavzor). Treatment of manic episodes with bipolar disorders, complex partial seizures. Prophylaxis of migraine headaches. OFF-LABEL: Refractory status epilepticus, diabetic neuropathy.

Precautions

Contraindications: Active hepatic disease, urea cycle disorders. Cautions: History of hepatic disease, bleeding abnormalities, pts at high risk for suicide, elderly.

 ​Lifespan considerations

Pregnancy/Lactation: Drug crosses placenta; is distributed in breast milk. Pregnancy Category D. Children: Increased risk of hepatotoxicity in pts younger than 2 yrs. Elderly: No age-related precautions, but lower dosages recommended.

Interactions

DRUG: Carbapenems (e.g., meropenem), CYP3A4 inducers (e.g., carbamazepine, phenytoin) may decrease concentration/effects. May alter effects of warfarin. May increase concentration of lamotrigine. Topiramate may increase risk of elevated serum ammonia levels. HERBAL: Evening primrose may decrease seizure threshold. FOOD: None known. LAB VALUES: May increase serum LDH, bilirubin, AST, ALT. Therapeutic serum level: 50–100 mcg/ml; toxic serum level: greater than 100 mcg/ml.

Availability (Rx)

Capsules (Depakene): 250 mg. Capsules, Sprinkle (Depakote Sprinkle): 125 mg. Injection, Solution (Depacon): 100 mg/ml. Syrup (Depakene): 250 mg/5 ml.

 Capsules, Delayed-Release (Stavzor): 125 mg, 250 mg, 500 mg.  Tablets, Delayed-Release (Depakote): 125 mg, 250 mg, 500 mg.  Tablets, Extended-Release (Depakote ER): 250 mg, 500 mg.

Reconstitution • Dilute each single dose with at least 50 ml D₅W, 0.9% NaCl, or lactated Ringer’s.

Rate of Administration • Infuse over 60 min at rate of 20 mg/min or less. • Alternatively, single doses of up to 45 mg/kg given over 5–10 min (1.5–6 mg/kg/min).

Storage • Store vials at room temperature. • Diluted solutions stable for 24 hrs. • Discard unused portion.

IV incompatibilities

None known.

IV compatibilities

Cefepime, ceftazidime.

PO: ADULTS, ELDERLY, CHILDREN 10 YRS AND OLDER: Initially, 10–15 mg/kg/day in 1–3 divided doses. May increase by 5–10 mg/kg/day at weekly intervals up to 30–60 mg/kg/day. Usual adult dosage: 1,000–2,500 mg/day. (Stavzor): Initially, 10–15 mg/kg/day, may increase by 5–10 mg/kg/day at 1-wk intervals to achieve desired response. Maximum: 60 mg/kg/day.

IV: ADULTS, ELDERLY, CHILDREN: Same frequency as oral dose.

Side effects

Frequent: Epilepsy: Abdominal pain, irregular menses, diarrhea, transient alopecia, indigestion, nausea, vomiting, tremors, fluctuations in body weight. Mania (22%–19%): Nausea, drowsiness. Occasional: Epilepsy: Constipation, dizziness, drowsiness, headache, skin rash, unusual excitement, restlessness. Mania (12%–6%): Asthenia (loss of strength, energy), abdominal pain, dyspepsia (heartburn, indigestion, epigastric distress), rash. Rare: Epilepsy: Mood changes, diplopia, nystagmus, spots before eyes, unusual bleeding/bruising.

Adverse effects/toxic reactions

Hepatotoxicity may occur, particularly in first 6 mos of therapy. May be preceded by loss of seizure control, malaise, weakness, lethargy, anorexia, vomiting rather than abnormal serum hepatic function test results. Blood dyscrasias may occur.

Anticonvulsant: Review history of seizure disorder (intensity, frequency, duration, level of consciousness). Initiate safety measures, quiet dark environment. CBC should be performed before and 2 wks after therapy begins, then 2 wks following maintenance dose. Obtain baseline hepatic function tests. Antimanic: Assess behavior, appearance, emotional status, response to environment, speech pattern, thought content. Antimigraine: Question pt regarding onset, location, duration of migraine, possible precipitating symptoms.

Fixed-combination(s)

Diovan HCT: valsartan/hydrochlorothiazide (a diuretic): 80 mg/12.5 mg, 160 mg/12.5 mg, 160 mg/25 mg, 320 mg/12.5 mg, 320 mg/25 mg. Exforge: valsartan/amlodipine (a calcium channel blocker): 160 mg/5 mg, 160 mg/10 mg, 320 mg/5 mg, 320 mg/10 mg. Exforge HCT: valsartan/amlodipine (a calcium channel blocker)/hydrochlorothiazide (a diuretic): 160 mg/5 mg/12.5 mg, 160 mg/5 mg/25 mg, 160 mg/10 mg/12.5 mg, 160 mg/10 mg/25 mg, 320 mg/10 mg/25 mg. Valturna: valsartan/aliskiren (a direct renin inhibitor): 160 mg/150 mg, 320 mg/300 mg.

classification

PHARMACOTHERAPEUTIC: Angiotensin II receptor antagonist. CLINICAL: Antihypertensive (see p. 11C, 62C).

Action

Potent vasodilator. Blocks vasoconstrictor, aldosterone-secreting effects of angiotensin II, inhibiting binding of angiotensin II to AT₁ receptors. Therapeutic Effect: Produces vasodilation, decreases peripheral resistance, decreases B/P.

Pharmacokinetics

Poorly absorbed after PO administration. Food decreases peak plasma concentration. Protein binding: 95%. Metabolized in liver. Eliminated in feces (83%), urine (13%). Unknown if removed by hemodialysis. Half-life: 6 hrs.

Uses

Treatment of hypertension alone or in combination with other antihypertensives. Treatment of HF. Reduce mortality in high-risk pts (left ventricular failure/dysfunction) following MI.

Precautions

Contraindications: Concomitant use with aliskiren in pts with diabetes. Cautions: Concurrent use of potassium-sparing diuretics or potassium supplements, mild to severe hepatic impairment, unstented bilateral/unilateral renal artery stenosis, renal impairment, significant aortic/mitral stenosis.

 ​Lifespan considerations

Pregnancy/Lactation: May cause fetal harm. Unknown if distributed in breast milk. Pregnancy Category C (D if used in second or third trimester). Children: Safety and efficacy not established. Elderly: No age-related precautions noted.

Interactions

DRUG: NSAIDs may decrease antihypertensive effect. Potassium-sparing drugs, potassium supplements may increase serum potassium. Diuretics may produce additive hypotensive effects. HERBAL: Ginger, ginseng, licorice may worsen hypertension. Black cohosh, periwinkle may increase antihypertensive effects. FOOD: None known. LAB VALUES: May increase serum bilirubin, AST, ALT, BUN, creatinine, potassium. May decrease Hgb, Hct, WBC.

Availability (Rx)

Tablets: 40 mg, 80 mg, 160 mg, 320 mg.

• Give without regard to meals.

PO: ADULTS, ELDERLY: Initially, 80–160 mg/day in pts who are not volume depleted. Maximum: 320 mg/day. CHILDREN 6–16 YRS: Initially, 1.3 mg/kg once a day (Maximum: 40 mg). May increase up to 2.7 mg/kg once a day (Maximum: 160 mg/day).

Side effects

Rare (2%–1%): Insomnia, fatigue, heartburn, abdominal pain, dizziness, headache, diarrhea, nausea, vomiting, arthralgia, edema.

Adverse effects/toxic reactions

Overdosage may manifest as hypotension, tachycardia. Bradycardia occurs less often. Viral infection, upper respiratory tract infection (cough, pharyngitis, sinusitis, rhinitis) occur rarely.

Obtain B/P, apical pulse immediately before each dose, in addition to regular monitoring (be alert to fluctuations). If excessive reduction in B/P occurs, place pt in supine position, feet slightly elevated. Question for possibility of pregnancy. Assess medication history (esp. diuretic). Question for history of hepatic/renal impairment, renal artery stenosis, history of severe HF. Obtain baseline chemistries, blood counts.

classification

PHARMACOTHERAPEUTIC: Tricyclic glycopeptide antibiotic. CLINICAL: Antibiotic.

Action

Binds to bacterial cell walls, altering cell membrane permeability, inhibiting RNA synthesis. Therapeutic Effect: Bactericidal.

Pharmacokinetics

PO: Poorly absorbed from GI tract. Primarily eliminated in feces. Parenteral: Widely distributed (except CSF). Protein binding: 10%–50%. Primarily excreted unchanged in urine. Not removed by hemodialysis. Half-life: 4–11 hrs (increased in renal impairment).

Uses

Systemic: Treatment of infections caused by staphylococcal, streptococcal spp. bacteria. PO: Treatment of antibiotic colitis, pseudomembranous colitis, antibiotic-associated diarrhea produced by C. difficile staphylococcal enterocolitis. OFF-LABEL: Treatment of infections caused by gram-positive organisms in pts with serious allergies to beta-lactam antibiotics; treatment of beta-lactam-resistant gram-positive infections.

Precautions

Contraindications: None known. Cautions: Renal impairment; concurrent therapy with other ototoxic, nephrotoxic medications.

 ​Lifespan considerations

Pregnancy/Lactation: Drug crosses placenta. Unknown if distributed in breast milk. Pregnancy Category C (injection), B (PO). Children: Close monitoring of serum levels recommended in premature neonates, young infants. Elderly: Age-related renal impairment may increase risk of ototoxicity, nephrotoxicity; dosage adjustment recommended.

Interactions

DRUG: Aminoglycosides, amphotericin B, cisplatin may increase risk of ototoxicity, nephrotoxicity of parenteral vancomycin. HERBAL: None significant. FOOD: None known. LAB VALUES: May increase BUN. Therapeutic peak serum level: (Not routinely obtained) 20–40 mcg/ml; therapeutic trough serum level: 10–20 mcg/ml. Toxic peak serum level: greater than 40 mcg/ml; toxic trough serum level: greater than 20 mcg/ml.

Availability (Rx)

Capsules (Vancocin): 125 mg, 250 mg. Infusion (Premix [Vancocin HCl]): 500 mg/100 ml, 1 g/200 ml. Injection, Powder for Reconstitution (Vancocin HCl): 500 mg, 750 mg, 1 g.

◀ ALERT ▶ Give by intermittent IV infusion (piggyback) or continuous IV infusion. Do not give IV push (may result in exaggerated hypotension or “red man” syndrome).

Reconstitution • For intermittent IV infusion (piggyback), reconstitute each 500-mg vial with 10 ml Sterile Water for Injection (20 ml for 1-g vial) to provide concentration of 50 mg/ml. • Further dilute with D₅W or 0.9% NaCl to final concentration not to exceed 5 mg/ml.

Rate of Administration • Administer over 60 min or longer (30 min for each 500 mg recommended). • Monitor B/P closely during IV infusion.

Storage • Reconstituted vials are stable for 14 days at room temperature or if refrigerated. • Diluted solutions are stable for 14 days if refrigerated or 7 days at room temperature. • Discard if precipitate forms.

IV incompatibilities

Albumin, amphotericin B complex (Abelcet, AmBisome, Amphotec), aztreonam (Azactam), cefazolin (Ancef), cefotaxime (Claforan), cefoxitin (Mefoxin), ceftazidime (Fortaz), ceftriaxone (Rocephin), cefuroxime (Zinacef), foscarnet (Foscavir), heparin, nafcillin (Nafcil), piperacillin and tazobactam (Zosyn).

IV compatibilities

Amiodarone (Cordarone), calcium gluconate, dexmedetomidine (Precedex), diltiazem (Cardizem), hydromorphone (Dilaudid), insulin, lorazepam (Ativan), magnesium sulfate, midazolam (Versed), morphine, nicardipine (Cardene), potassium chloride, propofol (Diprivan).

IV: ADULTS, ELDERLY: 10–20 mg/kg/dose q8–12h. Dosage requires adjustment in renal impairment. CHILDREN OLDER THAN 1 MO: 10–15 mg/kg/dose q6h. NEONATES: 15 mg/kg q24h up to 10–15 mg/kg/dose q6–8h.

Side effects

Frequent: PO: Bitter/unpleasant taste, nausea, vomiting, mouth irritation (with oral solution). Rare: Parenteral: Phlebitis, thrombophlebitis, pain at peripheral IV site, dizziness, vertigo, tinnitus, chills, fever, rash, necrosis with extravasation. PO: Rash.

Adverse effects/toxic reactions

Nephrotoxicity (acute kidney injury, acute tubular necrosis, renal failure), ototoxicity (temporary or permanent hearing loss) may occur. “Red man syndrome” or “red neck syndrome” is common adverse reaction characterized by pruritus, urticaria, erythema, angioedema, tachycardia, hypotension, myalgia, maculopapular rash (usually appears on face, neck, upper torso). Cardiovascular toxicity (cardiac depression, arrest) occurs rarely. Onset usually occurs within 30 min of start of infusion, resolves within hrs following infusion. May result from too-rapid rate of infusion.

Avoid other ototoxic, nephrotoxic medications if possible. Obtain culture, sensitivity test before giving first dose (therapy may begin before results are known).

classification

PHARMACOTHERAPEUTIC: Tyrosine kinase inhibitor. CLINICAL: Antineoplastic (see p. 91C).

Action

Inhibits epidermal growth factor (EGF)-stimulated receptor tyrosine kinase phosphorylation in tumor cells and endothelial cells. Inhibits cell migration, proliferation, survival, and angiogenesis (new blood vessel formation). Therapeutic Effect: Inhibits thyroid tumor cell growth and metastasis.

Pharmacokinetics

Slowly absorbed following PO administration. Peak concentration: 4–10 hrs. Metabolized in liver. Protein binding: 90%. Excreted in feces (44%), urine (25%). Half-life: 19 days.

Uses

Treatment of symptomatic or progressive medullary thyroid cancer in pts with unresectable locally advanced or metastatic disease.

Precautions

Contraindications: Congenital long QT syndrome. Cautions: Pregnancy, concurrent medications that prolong QT interval, strong CYP3A4 inducers, thyroid, cerebrovascular disease, bradyarrhythmias, moderate to severe renal/hepatic impairment, hypertension, uncompensated HF, history of torsade de pointes.

 ​Lifespan considerations

Pregnancy/Lactation: May cause fetal harm. Avoid pregnancy. Must use effective contraception during treatment and for at least 4 mos after treatment. Unknown if distributed in breast milk. Pregnancy Category D. Children: Safety and efficacy not established. Elderly: No age-related precautions noted.

Interactions

DRUG: Medications prolonging QT interval (e.g., azithromycin, amiodarone, clarithromycin, erythromycin, ciprofloxacin, haloperidol) may increase risk of QT prolongation. CYP3A4 inducers (e.g., carbamazepine, oxcarbazepine, phenytoin, rifampin) may decrease concentration/effects. HERBAL: St. John’s wort may decrease effectiveness. FOOD: Grapefruit products may increase risk of torsades, myelotoxicity. LAB VALUES: May decrease WBC, Hgb, neutrophils. May increase serum bilirubin, AST, ALT, creatinine, urine protein. May alter serum calcium, glucose, magnesium, potassium.

Availability (Rx)

Tablets: 100 mg, 300 mg.

• Give without regard to food. • Do not crush. • May disperse in 2 oz of non-carbonated water and stir for 10 min until tablet is evenly dispersed (will not completely dissolve). May administer dispersion immediately. Can be given via feeding tube. • Direct contact of crushed tablets with skin or mucous membranes should be strictly avoided. If contact occurs, wash thoroughly.

Storage • Contact pharmacy to properly discard out-of-date tablets.

PO: ADULTS, ELDERLY: 300 mg once daily.

Side effects

Frequent (57%–21%): Diarrhea/colitis, rash, dermatitis acneiform/acne, nausea, headache, fatigue, anorexia, abdominal pain. Occasional (15%–10%): Dry skin, vomiting, asthenia (loss of strength, energy), photosensitivity, insomnia, nasopharyngitis, dyspepsia, cough, pruritus, weight decrease, depression.

Adverse effects/toxic reactions

Prolonged QT interval resulting in torsade de pointes, ventricular arrhythmias, sudden cardiac death have been reported. Frequent diarrhea may result in electrolyte imbalances. Severe skin reactions, including Stevens-Johnson syndrome, have been reported. Interstitial lung disease (ILD) or pneumonitis reported (may result in respiratory-related death). Consider ILD in pts with hypoxia, pleural effusion, cough, dyspnea. Ischemic cerebrovascular events have been reported. Life-threatening events including hypertensive crisis, reversible posterior leukoencephalopathy syndrome (RPLS) have been noted. Adverse reactions resulting in death included respiratory failure/arrest, aspiration pneumonia, cardiac failure, sepsis, GI bleeding.

Obtain CBC with differential, serum chemistries, magnesium, ionized calcium, TSH, UA, EKG, vital signs. Obtain negative urine pregnancy before therapy. Question for history of congenital long QT syndrome, HF, arrhythmias, hepatic/renal impairment, seizures, CVA, hemorrhagic events, HTN. Obtain full medication history including contraception. Perform full head-to-toe exam including visual acuity, thorough skin assessment.

classification

PHARMACOTHERAPEUTIC: Phosphodiesterase inhibitor. CLINICAL: Erectile dysfunction adjunct.

Action

Inhibits phosphodiesterase type 5 (PDE5), the enzyme responsible for degrading cyclic guanosine monophosphate in corpus cavernosum of penis, resulting in smooth muscle relaxation, increased blood flow. Therapeutic Effect: Facilitates penile erection.

Pharmacokinetics

Rapidly absorbed after PO administration. Extensive tissue distribution. Protein binding: 95%. Metabolized in liver. Excreted in feces (91%–95%), urine (2%–6%). Drug has no effect on penile blood flow without sexual stimulation. Half-life: 4–5 hrs.

Uses

Treatment of erectile dysfunction.

Precautions

Contraindications: Concurrent use of nitrates in any form. Cautions: Renal/hepatic impairment, left ventricular outflow obstruction, cardiac disease, elderly, prolonged QT interval, anatomical deformation of penis, pts who may be predisposed to priapism (sickle cell anemia, multiple myeloma, leukemia), concurrent use with alpha-adrenergic blockers, CYP3A4 inhibitors, elderly.

 ​Lifespan considerations

Pregnancy/Lactation: Not indicated for use in women, newborns. Pregnancy Category B. Children: Not indicated for use in children. Elderly: No age-related precautions noted, but initial dose should be 5 mg.

Interactions

DRUG: Alpha-adrenergic blockers (e.g., alfuzosin, doxazosin, prazosin, tamsulosin, terazosin), nitrates may significantly lower B/P. CYP3A4 inhibitors (e.g., erythromycin, indinavir, itraconazole, ketoconazole, ritonavir) may increase concentration. HERBAL: None significant. FOOD: High-fat meals delay maximum effectiveness. Grapefruit products may increase concentration, risk of toxicity. LAB VALUES: May increase creatinine kinase, GGTP. May alter AST, ALT.

Availability (Rx)

Tablets (Levitra): 2.5 mg, 5 mg, 10 mg, 20 mg.

Tablets, Orally Disintegrating (Staxyn): 10 mg.

• May take approximately 1 hr before sexual activity. • May give without regard to food.

PO: ADULTS: 10 mg approximately 1 hr before sexual activity. Dose may be increased to 20 mg or decreased to 5 mg, based on pt tolerance. Maximum dosing frequency: Once daily. ELDERLY OLDER THAN 65 YRS: 5 mg. Orally disintegrating tablet: 10 mg 1 hr prior to sexual activity.

Side effects

Occasional: Headache, flushing, rhinitis, indigestion, sudden hearing loss. Rare (Less Than 2%): Dizziness, changes in color vision, blurred vision, postural hypotension.

Adverse effects/toxic reactions

Prolonged erections (lasting over 4 hrs), priapism (painful erections lasting over 6 hrs) occur rarely.

Assess cardiovascular status, medication history (esp. alpha-adrenergic blockers, nitrates) before initiating treatment for erectile dysfunction.

classification

PHARMACOTHERAPEUTIC: Selective partial nicotine agonist. CLINICAL: Smoking deterrent (see p. 156C).

Action

Binds to acetylcholine receptors, producing agonist activity, preventing nicotine from binding to specific receptors. Blocks ability of nicotine to stimulate central dopamine system, believed to be mechanism underlying reinforcement/reward experienced with smoking. Therapeutic Effect: Decreases desire to smoke.

Pharmacokinetics

Completely absorbed following PO administration. Absorption unaffected by food, time of day dosing. Maximum plasma concentration: 3–4 hrs; steady-state condition: within 4 days. Protein binding: 20%. Minimal metabolism. Removed by hemodialysis. Primarily excreted unchanged in urine. Half-life: 24 hrs.

Uses

Aid to smoking cessation treatment.

Precautions

Contraindications: None known. Cautions: Renal impairment, history of suicidal ideation, bipolar disorder, depression, schizophrenia.

 ​Lifespan considerations

Pregnancy/Lactation: Unknown if distributed in breast milk. Pregnancy Category C. Children: Not recommended. Elderly: Age-related renal impairment may require dosage adjustment.

Interactions

DRUG: Cimetidine may increase effect. HERBAL: None significant. FOOD: None known. LAB VALUES: None significant.

Availability

Tablets (Film-Coated): 0.5 mg, 1 mg.

Administration/handling

• Give with food and with full glass of water. • Do not break, crush, dissolve, or divide film-coated tablets.

Indications/routes/dosage

◀ ALERT ▶ Therapy should start 1 wk before stopping smoking.

Side effects

Frequent (30%–13%): Nausea, insomnia, headache, abnormal dreams. Occasional (8%–5%): Constipation, abdominal discomfort, fatigue, dry mouth, flatulence, altered taste, dyspepsia (heartburn, indigestion, epigastric pain), vomiting, anxiety, depression, irritability. Rare (3%–1%): Drowsiness, rash, increased appetite, lethargy, nightmares, gastroesophageal reflux disease, rhinorrhea, agitation, mood swings.

Adverse effects/toxic reactions

Abrupt withdrawal may cause irritability, sleep disturbances in 3% of pts. Hypertension, angina pectoris, arrhythmia, bradycardia, coronary artery disease, gingivitis, anemia, lymphadenopathy occur rarely. May cause bizarre behavior, suicidal ideation.

Screen, evaluate for coronary heart disease (history of MI, angina pectoris), cardiac arrhythmias, suicidal ideation.

classification

PHARMACOTHERAPEUTIC: Posterior pituitary hormone. CLINICAL: Vasopressor, antidiuretic.

Action

Increases reabsorption of water by renal tubules. Directly stimulates smooth muscle in GI tract. Therapeutic Effect: Causes peristalsis, vasoconstriction.

Pharmacokinetics

Route	Onset	Peak	Duration
IV	N/A	N/A	0.5–1 hr
IM, subcutaneous	1–2 hrs	N/A	2–8 hrs

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