Caspofungin Acetate

Based on animal data, caspofungin may cause fetal harm. There are insufficient human data to establish whether there is a drug-associated risk for major birth defects, miscarriage, or adverse maternal or fetal outcomes with caspofungin use in pregnant women.

In animal studies, caspofungin caused embryofetal toxicity, including increased resorptions, increased peri-implantation loss, and incomplete ossification at multiple fetal sites when administered intravenously to pregnant rats and rabbits during organogenesis at doses up to 0.8 and 2 times the clinical dose, respectively

. Advise patients of the potential risk to the fetus.

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

In animal reproduction studies, pregnant rats dosed intravenously with caspofungin during organogenesis (gestational days [GD] 6 to 20) at 0.5, 2, or 5 mg/kg/day (up to 0.8 times the clinical dose based on body surface area comparison) showed increased resorptions and peri-implantation losses at 5 mg/kg/day. Incomplete ossification of the skull and torso and increased incidences of cervical rib were noted in offspring born to pregnant rats treated at doses up to 5 mg/kg/day. In pregnant rabbits treated with intravenous caspofungin during organogenesis (GD 7 to 20) at doses of 1, 3, or 6 mg/kg/day (approximately 2 times the clinical dose based on body surface area comparison), increased fetal resorptions and increased incidence of incomplete ossification of the talus/calcaneus in offspring were observed at the highest dose tested. Caspofungin crossed the placenta in rats and rabbits and was detectable in fetal plasma.

In peri- and postnatal development study in rats, intravenous caspofungin administered at 0.5, 2 or 5 mg/kg/day from Day 6 of gestation through Day 20 of lactation was not associated with any adverse effects on reproductive performance or subsequent development of first generation (F1) offspring or malformations in second generation (F2) offspring.

The safety and effectiveness of caspofungin in pediatric patients 3 months to 17 years of age are supported by evidence from adequate and well-controlled studies in adults, pharmacokinetic data in pediatric patients, and additional data from prospective studies in pediatric patients 3 months to 17 years of age for the following indications

:

• Empirical therapy for presumed fungal infections in febrile, neutropenic patients.

• Treatment of candidemia and the following Candida infections: intra-abdominal abscesses, peritonitis, and pleural space infections.

• Treatment of esophageal candidiasis.

• Treatment of invasive aspergillosis in patients who are refractory to or intolerant of other therapies (e.g., amphotericin B, lipid formulations of amphotericin B, itraconazole).



The efficacy and safety of caspofungin has not been adequately studied in prospective clinical trials involving neonates and infants under 3 months of age. Although limited pharmacokinetic data were collected in neonates and infants below 3 months of age, these data are insufficient to establish a safe and effective dose of caspofungin in the treatment of neonatal candidiasis. Invasive candidiasis in neonates has a higher rate of CNS and multi-organ involvement than in older patients; the ability of caspofungin to penetrate the blood-brain barrier and to treat patients with meningitis and endocarditis is unknown.

Caspofungin has not been studied in pediatric patients with endocarditis, osteomyelitis, and meningitis due to Candida. Caspofungin has also not been studied as initial therapy for invasive aspergillosis in pediatric patients.

In clinical trials, 171 pediatric patients (0 months to 17 years of age), including 18 patients who were less than 3 months of age, were given intravenous caspofungin. Pharmacokinetic studies enrolled a total of 66 pediatric patients, and an additional 105 pediatric patients received caspofungin in safety and efficacy studies

. The majority of the pediatric patients received caspofungin at a once-daily maintenance dose of 50 mg/m2 for a mean duration of 12 days (median 9, range 1 to 87 days). In all studies, safety was assessed by the investigator throughout study therapy and for 14 days following cessation of study therapy. The most common adverse reactions in pediatric patients treated with caspofungin were pyrexia (29%), blood potassium decreased (15%), diarrhea (14%), increased aspartate aminotransferase (12%), rash (12%), increased alanine aminotransferase (11%), hypotension (11%), and chills (11%).

Postmarketing hepatobiliary adverse reactions have been reported in pediatric patients with serious underlying medical conditions.

Adult patients with mild hepatic impairment (Child-Pugh score 5 to 6) do not need a dosage adjustment. For adult patients with moderate hepatic impairment (Child-Pugh score 7 to 9), caspofungin acetate for injection 35 mg once daily is recommended based upon pharmacokinetic data

with a 70 mg loading dose administered on Day 1 where appropriate. There is no clinical experience in adult patients with severe hepatic impairment (Child-Pugh score greater than 9) and in pediatric patients with any degree of hepatic impairment.

Adult patients with mild hepatic impairment (Child-Pugh score 5 to 6) do not need a dosage adjustment. For adult patients with moderate hepatic impairment (Child-Pugh score 7 to 9), caspofungin 35 mg once daily is recommended based upon pharmacokinetic data

. However, where recommended, a 70 mg loading dose should still be administered on Day 1. There is no clinical experience in adult patients with severe hepatic impairment (Child-Pugh score greater than 9) and in pediatric patients 3 months to 17 years of age with any degree of hepatic impairment.

Adult patients with mild hepatic impairment (Child-Pugh score 5 to 6) do not need a dosage adjustment. For adult patients with moderate hepatic impairment (Child-Pugh score 7 to 9), caspofungin 35 mg once daily is recommended based upon pharmacokinetic data

. However, where recommended, a 70 mg loading dose should still be administered on Day 1. There is no clinical experience in adult patients with severe hepatic impairment (Child-Pugh score greater than 9) and in pediatric patients 3 months to 17 years of age with any degree of hepatic impairment.

Adult and pediatric pharmacokinetic parameters are presented in Table 8.

Plasma concentrations of caspofungin decline in a polyphasic manner following single 1-hour IV infusions. A short α-phase occurs immediately postinfusion, followed by a β-phase (half-life of 9 to 11 hours) that characterizes much of the profile and exhibits clear log-linear behavior from 6 to 48 hours postdose during which the plasma concentration decreases 10-fold. An additional, longer half-life phase, γ-phase, (half-life of 40 to 50 hours), also occurs. Distribution, rather than excretion or biotransformation, is the dominant mechanism influencing plasma clearance. Caspofungin is extensively bound to albumin (~97%), and distribution into red blood cells is minimal. Mass balance results showed that approximately 92% of the administered radioactivity was distributed to tissues by 36 to 48 hours after a single 70 mg dose of [3H] caspofungin acetate. There is little excretion or biotransformation of caspofungin during the first 30 hours after administration.

Caspofungin is slowly metabolized by hydrolysis and N-acetylation. Caspofungin also undergoes spontaneous chemical degradation to an open-ring peptide compound, L-747969. At later time points (≥5 days postdose), there is a low level (≤7 picomoles/mg protein, or ≤1.3% of administered dose) of covalent binding of radiolabel in plasma following single-dose administration of [3H] caspofungin acetate, which may be due to two reactive intermediates formed during the chemical degradation of caspofungin to L-747969. Additional metabolism involves hydrolysis into constitutive amino acids and their degradates, including dihydroxyhomotyrosine and N-acetyl-dihydroxyhomotyrosine. These two tyrosine derivatives are found only in urine, suggesting rapid clearance of these derivatives by the kidneys.

Two single-dose radiolabeled pharmacokinetic studies were conducted. In one study, plasma, urine, and feces were collected over 27 days, and in the second study plasma was collected over 6 months. Plasma concentrations of radioactivity and of caspofungin were similar during the first 24 to 48 hours postdose; thereafter drug levels fell more rapidly. In plasma, caspofungin concentrations fell below the limit of quantitation after 6 to 8 days postdose, while radiolabel fell below the limit of quantitation at 22.3 weeks postdose. After single intravenous administration of [3H] caspofungin acetate, excretion of caspofungin and its metabolites in humans was 35% of dose in feces and 41% of dose in urine. A small amount of caspofungin is excreted unchanged in urine (~1.4% of dose). Renal clearance of parent drug is low (~0.15 mL/min) and total clearance of caspofungin is 12 mL/min.

In a clinical study of single 70 mg doses, caspofungin pharmacokinetics were similar in healthy adult volunteers with mild renal impairment (creatinine clearance 50 to 80 mL/min) and control subjects. Moderate (creatinine clearance 31 to 49 mL/min), severe (creatinine clearance 5 to 30 mL/min), and end-stage (creatinine clearance less than 10 mL/min and dialysis dependent) renal impairment moderately increased caspofungin plasma concentrations after single-dose administration (range: 30 to 49% for AUC). However, in adult patients with invasive aspergillosis, candidemia, or other Candida infections (intra-abdominal abscesses, peritonitis, or pleural space infections) who received multiple daily doses of caspofungin 50 mg, there was no significant effect of mild to end-stage renal impairment on caspofungin concentrations. No dosage adjustment is necessary for patients with renal impairment. Caspofungin is not dialyzable, thus supplementary dosing is not required following hemodialysis.

Plasma concentrations of caspofungin after a single 70 mg dose in adult patients with mild hepatic impairment (Child-Pugh score 5 to 6) were increased by approximately 55% in AUC compared to healthy control subjects. In a 14-day multiple-dose study (70 mg on Day 1 followed by 50 mg daily thereafter), plasma concentrations in adult patients with mild hepatic impairment were increased modestly (19 to 25% in AUC) on Days 7 and 14 relative to healthy control subjects. No dosage adjustment is recommended for patients with mild hepatic impairment.



Adult patients with moderate hepatic impairment (Child-Pugh score 7 to 9) who received a single 70 mg dose of caspofungin had an average plasma caspofungin increase of 76% in AUC compared to control subjects. A dosage reduction is recommended for adult patients with moderate hepatic impairment based upon these pharmacokinetic data.

There is no clinical experience in adult patients with severe hepatic impairment (Child-Pugh score greater than 9) or in pediatric patients with any degree of hepatic impairment.

Plasma concentrations of caspofungin in healthy adult men and women were similar following a single 70 mg dose. After 13 daily 50 mg doses, caspofungin plasma concentrations in women were elevated slightly (approximately 22% in area under the curve [AUC]) relative to men. No dosage adjustment is necessary based on gender.

Regression analyses of patient pharmacokinetic data indicated that no clinically significant differences in the pharmacokinetics of caspofungin were seen among Caucasians, Blacks, and Hispanics. No dosage adjustment is necessary on the basis of race.

Plasma concentrations of caspofungin in healthy older men and women (65 years of age and older) were increased slightly (approximately 28% AUC) compared to young healthy men after a single 70 mg dose of caspofungin. In patients who were treated empirically or who had candidemia or other Candida infections (intra-abdominal abscesses, peritonitis, or pleural space infections), a similar modest effect of age was seen in older patients relative to younger patients. No dosage adjustment is necessary for the elderly.





Caspofungin has been studied in five prospective studies involving pediatric patients under 18 years of age, including three pediatric pharmacokinetic studies [initial study in adolescents (12 - 17 years of age) and children (2 - 11 years of age) followed by a study in younger patients (3 - 23 months of age) and then followed by a study in neonates and infants (less than 3 months of age)]

.

Pharmacokinetic parameters following multiple doses of caspofungin in pediatric and adult patients are presented in Table 8.

Population	N	Daily Dose	Pharmacokinetic Parameters (Mean ± Standard Deviation)
			AUC0-24hr ( mcg∙hr/mL)		C1hr ( mcg/mL)	C24hr ( mcg/mL)	t1/2 (hr)*	CI (mL/min)
PEDIATRIC PATIENTS
Adolescents, Aged 12-17 years	8	50 mg/m2		124.9 ± 50.4	14.0 ± 6.9	2.4 ± 1.0	11.2 ± 1.7	12.6 ± 5.5
Children, Aged 2-11 years	9	50 mg/m2		120.0 ± 33.4	16.1 ± 4.2	1.7 ± 0.8	8.2 ± 2.4	6.4 ± 2.6
Young Children, Aged 3-23 months	8	50 mg/m2		131.2 ± 17.7	17.6 ± 3.9	1.7 ± 0.7	8.8 ± 2.1	3.2 ± 0.4
ADULT PATIENTS
Adults with Esophageal Candidiasis	6 †	50 mg		87.3 ± 30.0	8.7 ± 2.1	1.7 ± 0.7	13.0 ± 1.9	10.6 ± 3.8
Adults receiving Empirical Therapy	119 ‡	50 mg §		--	8.0 ± 3.4	1.6 ± 0.7	--	--
* Harmonic Mean ± jackknife standard deviation † N=5 for C1hrand AUC0-24hr; N=6 for C24hr ‡ N=117 for C24hr; N=119 for C1hr § Following an initial 70 mg loading dose on day 1

Studies in vitro show that caspofungin acetate is not an inhibitor of any enzyme in the cytochrome P (CYP) system. Caspofungin is not a substrate for P-glycoprotein and is a poor substrate for CYP enzymes.



In clinical studies, caspofungin did not induce the CYP3A4 metabolism of other drugs. Clinical studies in adult healthy volunteers also demonstrated that the pharmacokinetics of caspofungin are not altered by itraconazole, amphotericin B, mycophenolate, nelfinavir, or tacrolimus. Caspofungin has no effect on the pharmacokinetics of itraconazole, amphotericin B, or the active metabolite of mycophenolate.

: In two adult clinical studies, cyclosporine (one 4 mg/kg dose or two 3 mg/kg doses) increased the AUC of caspofungin by approximately 35%. Caspofungin did not increase the plasma levels of cyclosporine. There were transient increases in liver ALT and AST when caspofungin and cyclosporine were co-administered.

: Caspofungin reduced the blood AUC_{0 - 12}of tacrolimus (FK-506, Prograf^®) by approximately 20%, peak blood concentration (C_max) by 16%, and 12-hour blood concentration (C_12hr) by 26% in healthy adult subjects when tacrolimus (2 doses of 0.1 mg/kg 12 hours apart) was administered on the 10th day of caspofungin 70 mg daily, as compared to results from a control period in which tacrolimus was administered alone. For patients receiving both therapies, standard monitoring of tacrolimus whole blood trough concentrations and appropriate tacrolimus dosage adjustments are recommended.

: A drug-drug interaction study with rifampin in adult healthy volunteers has shown a 30% decrease in caspofungin trough concentrations.

Adults: Results from regression analyses of adult patient pharmacokinetic data suggest that co-administration of other hepatic CYP enzyme inducers (e.g., efavirenz, nevirapine, phenytoin, dexamethasone, or carbamazepine) with caspofungin may result in clinically meaningful reductions in caspofungin concentrations. It is not known which drug clearance mechanism involved in caspofungin disposition may be inducible.

: In pediatric patients, results from regression analyses of pharmacokinetic data suggest that co-administration of dexamethasone with caspofungin may result in clinically meaningful reductions in caspofungin trough concentrations. This finding may indicate that pediatric patients will have similar reductions with inducers as seen in adults.

Adult and pediatric pharmacokinetic parameters are presented in Table 8.

Plasma concentrations of caspofungin decline in a polyphasic manner following single 1-hour IV infusions. A short α-phase occurs immediately postinfusion, followed by a β-phase (half-life of 9 to 11 hours) that characterizes much of the profile and exhibits clear log-linear behavior from 6 to 48 hours postdose during which the plasma concentration decreases 10-fold. An additional, longer half-life phase, γ-phase, (half-life of 40 to 50 hours), also occurs. Distribution, rather than excretion or biotransformation, is the dominant mechanism influencing plasma clearance. Caspofungin is extensively bound to albumin (~97%), and distribution into red blood cells is minimal. Mass balance results showed that approximately 92% of the administered radioactivity was distributed to tissues by 36 to 48 hours after a single 70 mg dose of [3H] caspofungin acetate. There is little excretion or biotransformation of caspofungin during the first 30 hours after administration.

Caspofungin is slowly metabolized by hydrolysis and N-acetylation. Caspofungin also undergoes spontaneous chemical degradation to an open-ring peptide compound, L-747969. At later time points (≥5 days postdose), there is a low level (≤7 picomoles/mg protein, or ≤1.3% of administered dose) of covalent binding of radiolabel in plasma following single-dose administration of [3H] caspofungin acetate, which may be due to two reactive intermediates formed during the chemical degradation of caspofungin to L-747969. Additional metabolism involves hydrolysis into constitutive amino acids and their degradates, including dihydroxyhomotyrosine and N-acetyl-dihydroxyhomotyrosine. These two tyrosine derivatives are found only in urine, suggesting rapid clearance of these derivatives by the kidneys.

Two single-dose radiolabeled pharmacokinetic studies were conducted. In one study, plasma, urine, and feces were collected over 27 days, and in the second study plasma was collected over 6 months. Plasma concentrations of radioactivity and of caspofungin were similar during the first 24 to 48 hours postdose; thereafter drug levels fell more rapidly. In plasma, caspofungin concentrations fell below the limit of quantitation after 6 to 8 days postdose, while radiolabel fell below the limit of quantitation at 22.3 weeks postdose. After single intravenous administration of [3H] caspofungin acetate, excretion of caspofungin and its metabolites in humans was 35% of dose in feces and 41% of dose in urine. A small amount of caspofungin is excreted unchanged in urine (~1.4% of dose). Renal clearance of parent drug is low (~0.15 mL/min) and total clearance of caspofungin is 12 mL/min.

In a clinical study of single 70 mg doses, caspofungin pharmacokinetics were similar in healthy adult volunteers with mild renal impairment (creatinine clearance 50 to 80 mL/min) and control subjects. Moderate (creatinine clearance 31 to 49 mL/min), severe (creatinine clearance 5 to 30 mL/min), and end-stage (creatinine clearance less than 10 mL/min and dialysis dependent) renal impairment moderately increased caspofungin plasma concentrations after single-dose administration (range: 30 to 49% for AUC). However, in adult patients with invasive aspergillosis, candidemia, or other Candida infections (intra-abdominal abscesses, peritonitis, or pleural space infections) who received multiple daily doses of caspofungin 50 mg, there was no significant effect of mild to end-stage renal impairment on caspofungin concentrations. No dosage adjustment is necessary for patients with renal impairment. Caspofungin is not dialyzable, thus supplementary dosing is not required following hemodialysis.

Plasma concentrations of caspofungin after a single 70 mg dose in adult patients with mild hepatic impairment (Child-Pugh score 5 to 6) were increased by approximately 55% in AUC compared to healthy control subjects. In a 14-day multiple-dose study (70 mg on Day 1 followed by 50 mg daily thereafter), plasma concentrations in adult patients with mild hepatic impairment were increased modestly (19 to 25% in AUC) on Days 7 and 14 relative to healthy control subjects. No dosage adjustment is recommended for patients with mild hepatic impairment.



Adult patients with moderate hepatic impairment (Child-Pugh score 7 to 9) who received a single 70 mg dose of caspofungin had an average plasma caspofungin increase of 76% in AUC compared to control subjects. A dosage reduction is recommended for adult patients with moderate hepatic impairment based upon these pharmacokinetic data.

There is no clinical experience in adult patients with severe hepatic impairment (Child-Pugh score greater than 9) or in pediatric patients with any degree of hepatic impairment.

Plasma concentrations of caspofungin in healthy adult men and women were similar following a single 70 mg dose. After 13 daily 50 mg doses, caspofungin plasma concentrations in women were elevated slightly (approximately 22% in area under the curve [AUC]) relative to men. No dosage adjustment is necessary based on gender.

Regression analyses of patient pharmacokinetic data indicated that no clinically significant differences in the pharmacokinetics of caspofungin were seen among Caucasians, Blacks, and Hispanics. No dosage adjustment is necessary on the basis of race.

Plasma concentrations of caspofungin in healthy older men and women (65 years of age and older) were increased slightly (approximately 28% AUC) compared to young healthy men after a single 70 mg dose of caspofungin. In patients who were treated empirically or who had candidemia or other Candida infections (intra-abdominal abscesses, peritonitis, or pleural space infections), a similar modest effect of age was seen in older patients relative to younger patients. No dosage adjustment is necessary for the elderly.





Caspofungin has been studied in five prospective studies involving pediatric patients under 18 years of age, including three pediatric pharmacokinetic studies [initial study in adolescents (12 - 17 years of age) and children (2 - 11 years of age) followed by a study in younger patients (3 - 23 months of age) and then followed by a study in neonates and infants (less than 3 months of age)]

.

Pharmacokinetic parameters following multiple doses of caspofungin in pediatric and adult patients are presented in Table 8.

Population	N	Daily Dose	Pharmacokinetic Parameters (Mean ± Standard Deviation)
			AUC0-24hr ( mcg∙hr/mL)		C1hr ( mcg/mL)	C24hr ( mcg/mL)	t1/2 (hr)*	CI (mL/min)
PEDIATRIC PATIENTS
Adolescents, Aged 12-17 years	8	50 mg/m2		124.9 ± 50.4	14.0 ± 6.9	2.4 ± 1.0	11.2 ± 1.7	12.6 ± 5.5
Children, Aged 2-11 years	9	50 mg/m2		120.0 ± 33.4	16.1 ± 4.2	1.7 ± 0.8	8.2 ± 2.4	6.4 ± 2.6
Young Children, Aged 3-23 months	8	50 mg/m2		131.2 ± 17.7	17.6 ± 3.9	1.7 ± 0.7	8.8 ± 2.1	3.2 ± 0.4
ADULT PATIENTS
Adults with Esophageal Candidiasis	6 †	50 mg		87.3 ± 30.0	8.7 ± 2.1	1.7 ± 0.7	13.0 ± 1.9	10.6 ± 3.8
Adults receiving Empirical Therapy	119 ‡	50 mg §		--	8.0 ± 3.4	1.6 ± 0.7	--	--
* Harmonic Mean ± jackknife standard deviation † N=5 for C1hrand AUC0-24hr; N=6 for C24hr ‡ N=117 for C24hr; N=119 for C1hr § Following an initial 70 mg loading dose on day 1

Studies in vitro show that caspofungin acetate is not an inhibitor of any enzyme in the cytochrome P (CYP) system. Caspofungin is not a substrate for P-glycoprotein and is a poor substrate for CYP enzymes.



In clinical studies, caspofungin did not induce the CYP3A4 metabolism of other drugs. Clinical studies in adult healthy volunteers also demonstrated that the pharmacokinetics of caspofungin are not altered by itraconazole, amphotericin B, mycophenolate, nelfinavir, or tacrolimus. Caspofungin has no effect on the pharmacokinetics of itraconazole, amphotericin B, or the active metabolite of mycophenolate.

: In two adult clinical studies, cyclosporine (one 4 mg/kg dose or two 3 mg/kg doses) increased the AUC of caspofungin by approximately 35%. Caspofungin did not increase the plasma levels of cyclosporine. There were transient increases in liver ALT and AST when caspofungin and cyclosporine were co-administered.

: Caspofungin reduced the blood AUC_{0 - 12}of tacrolimus (FK-506, Prograf^®) by approximately 20%, peak blood concentration (C_max) by 16%, and 12-hour blood concentration (C_12hr) by 26% in healthy adult subjects when tacrolimus (2 doses of 0.1 mg/kg 12 hours apart) was administered on the 10th day of caspofungin 70 mg daily, as compared to results from a control period in which tacrolimus was administered alone. For patients receiving both therapies, standard monitoring of tacrolimus whole blood trough concentrations and appropriate tacrolimus dosage adjustments are recommended.

: A drug-drug interaction study with rifampin in adult healthy volunteers has shown a 30% decrease in caspofungin trough concentrations.

Adults: Results from regression analyses of adult patient pharmacokinetic data suggest that co-administration of other hepatic CYP enzyme inducers (e.g., efavirenz, nevirapine, phenytoin, dexamethasone, or carbamazepine) with caspofungin may result in clinically meaningful reductions in caspofungin concentrations. It is not known which drug clearance mechanism involved in caspofungin disposition may be inducible.

: In pediatric patients, results from regression analyses of pharmacokinetic data suggest that co-administration of dexamethasone with caspofungin may result in clinically meaningful reductions in caspofungin trough concentrations. This finding may indicate that pediatric patients will have similar reductions with inducers as seen in adults.

Anaphylaxis and other hypersensitivity reactions have been reported during administration of caspofungin.

Possible histamine-mediated adverse reactions, including rash, facial swelling, angioedema, pruritus, sensation of warmth or bronchospasm have been reported.

Cases of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), some with a fatal outcome, have been reported with use of caspofungin

.

Discontinue caspofungin at the first sign or symptom of a hypersensitivity reaction and administer appropriate treatment.